Apple A8X vs Tegra K1 vs Snapdragon 805 - Tablet SoC Comprarison (2014 Edition)

In the last few years, ultra-mobile System-on-Chip processors have made unprecedented strides in terms of performance and efficiency, advancing very quickly the standards for mobile performance. One form factor that particularly benefits from the exponential growth of SoC performance are tablets, since their large screens allow for the processors' abilities to be fully utilized. For the holiday season of 2014, we have the latest and greatest of mobile performance shipping inside high-end tablets. Apple has made a whole new SoC just for their iPad Air 2 tablet, which they call the A8X. Nvidia's Tegra K1 processor, which borrows Nvidia's venerable Kepler GPU architecture, has also appeared on a number of new high-end tablets. Finally, we also have the Qualcomm Snapdragon 805 processor found in the Amazon Kindle Fire HDX 8.9" (2014). Unfortunately, most other tablets either use the aging Snapdragon 801 processor, or in the case of Samsung's latest high-end tablets, use an even older Snapdragon 800 processor or the also old Exynos 5420 processor, which debuted with the Note 3 phablet in late 2013. In any case, at the pinnacle of tablet performance, we have the Apple A8X, the Tegra K1 and the Snapdragon 805 battling for the top spot.

	Apple A8X	Nvidia Tegra K1	Snapdragon 805
Process Node	20nm	28nm HPM	28nm HPM
CPU	Tri-core "Enhanced Cyclone" (64-bit) @ 1.5GHz	32-bit: Quad-core ARM Cortex A15 @ 2.3GHz  64-bit: Dual-core Denver @ 2.5GHZ	Quad-core Krait 450 @ 2.5GHz
GPU	PoverVR GXA6850 @ 450MHz (230 GFLOPS)	192-core Kepler GPU @ 852MHz (327 GFLOPS)	Adreno 420 @ 600MHz (172.8 GFLOPS)
Memory Interface	64-bit Dual-channel LPDDR3-1600 (25.6GB/s)	64-bit Dual-channel LPDDR3-1066 (17GB/s)	64-bit Dual-channel LPDDR3-1600 (25.6GB/s)

The CPU

It can certainly be said that all of this year's high-end mobile processors have excellent CPU performance. However, each manufacturer took a different path to reach those high performance demands, and that is what we'll be looking at in this section.

Starting with the A8X's CPU, what we have in hand is Apple's first CPU with more than two CPU cores. This time we have a Tri-core CPU, based on an updated revision of the Apple-designed Cyclone core, which utilizes the ARMv8 ISA and is therefore a 64-bit architecture. Clock speeds remain conservative with Apple's latest CPU, going no further than 1.5GHz. So with three cores at 1.5GHz, how does Apple get performance competitive with quad-core, 2GHz+ offerings from competitors? The answer lies within the Cyclone core.
The Cyclone CPU, now in its second generation, is a very wide core. As it is, it can issue up to 6 instructions per clock. Also, each Cyclone core contains 4 ALUs, as opposed to 2 ALUs/core in Apple's previous CPU architecture, Swift. Also, the reorder buffer has been increased to 192 instructions, in order to avoid memory stalls and to utilize more fully the 6 execution pipelines. In comparison, a Cortex-A15 core can co-issue up to 3 instructions per clock, half as much as Cyclone, and can hold up to 128 instructions in its reorder buffer, only two thirds of the amount that Cyclone's reorder buffer can hold.
By building a very wide CPU architecture, and keeping their CPUs to low core counts and clock speeds, Apple has, in one move, achieved excellent single-threaded performance, far beyond what a Cortex A15 or a Krait core can produce, while at least matching the quad-core competition in multi-threaded processing. I've always said that, due to the fact that CPU instructions tend to have a very threaded nature, CPUs should be way more efficient if they are built emphasizing single-threaded performance, and Apple continues to do the right thing with Cyclone.

The Snapdragon 805 is the last high-end SoC to utilize Qualcomm's own Krait CPU architecture, which was introduced WAY back with the Snapdragon S4. Needless to say, it's still a 32-bit core. The last revision of the Krait architecture is dubbed Krait 450. While Krait 450 carries many improvements compared to the original Krait core, the basic architecture is still the same. Like the Cortex-A15 it's based on, Krait is a 3-wide machine, capable of co-issuing up to 8 instructions at once. In comparison to Cyclone, it's a relatively small core, therefore, it won't be as fast in terms of single threaded performance. Krait 450's tweaked architecture allows it to run at a whopping 2.7GHz, or to be more exact, 2.65GHz. In the case of the Snapdragon 805, we have four of these Krait 450 cores. Qualcomm's signature architecture tweak, which involves putting each core on an individual voltage/frequency controller, allows each core to have a different frequency. That reduces the power consumption of the SoC, and should translate into better battery life. With four cores, and at such a high frequency, the Snapdragon 805's CPU gets very good multi-threaded performance, although the relatively narrow Krait core hurts single-threaded performance very much.

Finally, we have the Tegra K1 and its two different versions. The 32-bit version of the Tegra K1 employs a quad-core Cortex-A15 CPU clocked at up to 2.3GHz, and we've seen a CPU configuration like this in so many SoCs that by this point it's a very well known quantity. The interesting story here is the 64-bit Tegra K1, which uses a dual-core configuration of Nvidia's brand new custom CPU architecture, named Denver. If you don't care much to know about Denver's architecture, you'd better skip this section, because there is A LOT to say about Nvidia's custom CPU.

Denver: The Oddest CPU in SoC history

Denver is Nvidia's first attempt at making a proprietary CPU architecture, and for a first attempt it's actually very good. Some of Nvidia's expertise as a GPU maker has translated into its CPU architecture. For instance, exactly like with Nvidia's GPU architectures, Denver works with VLIW (Very Long Instruction Word) instructions. Basically, this means that the instructions are packed into a 32-bit long "word", and only then are sent into the execution pipelines.

Denver's most peculiar characteristic might be this one: it's an in-order machine, while basically every other high-end mobile CPU has Out-of-Order Execution (OoOE) capabilities. Denver's lack of a dedicated engine that reorders instructions in order to reduce memory stalls and therefore increase the IPC (Instructions Per Clock) should be a huge performance bottleneck. However, Nvidia employs a very interesting (and in my opinion unnecessarily complicated) way of dealing with its in-order architecture.

By not having a hardware OoOE engine built into the CPU, Nvidia has to rely on software tricks to reorder instructions and enhance ILP (Instruction Level Parallelism). Denver is actually not meant to decode ARM instructions most of the time. Rather, Nvidia chose to build a decoder that would run native instructions, optimized for maximum ILP. For this optimization to occur, Nvidia has implemented a Dynamic Code Optimizer (DCO). Basically, the DCO's job is to recognize ARM instructions that are being sent to the CPU frequently, translate it into native instructions and optimize the instruction by reordering parts of the instruction to reduce memory stalls and maximize ILP. For this to work, a small part of the device's internal storage must be reserved to store the optimized instructions.

One implication of this system is that the CPU must be able to decode both native instructions and normal ARM instructions. For this purpose there are two decoders in the CPU block. One huge 7-wide decoder for native instructions generated by the DCO, and a secondary 2-wide decoder for ARM instructions. The difference in size between the two decoders shows how Nvidia expects to have the native instructions being used most of the time. Of course, at the first time that a program is run, and there are no optimized native instructions ready for the native decoder to use, only the ARM decoder would be used until the DCO starts recognizing recurring ARM instructions from the program and optimizes those instructions, from which point onwards that specific instruction would always go through the native decoder. If a program ran the same instructions multiple times (for example, a benchmark program), eventually all of the program's instructions would have a corresponding native optimized instruction stored, and then only the native decoder would be utilized. That would correspond to Denver's peak performance scenario.

While Nvidia's architecture might be a very interesting move, I ask myself if it wouldn't just be easier to build a regular Out-of-Order machine. But still, if it performs well in real life, it doesn't really matter how odd Nvidia's approach was. 

Now, going on to the execution potion of the Denver machine, we see why Denver is the widest mobile CPU in existence. That title was previously held by Cyclone, with its 6 execution pipelines, however, Nvidia went a step ahead and produced a 7-wide machine, capable of co-issuing up to seven instructions at once. That alone should give the Denver core excellent single-threaded performance.

The 64-bit version of the Tegra K1 employs two Denver cores clocked at up to 2.5GHz. That makes it the SoC with the lowest core count among the ones being compared here. While single-threaded performance will most certainly be great, I'm not sure that the dual-core Denver CPU can outrun its triple-core and quad-core opponents.

In order to test that, let's start our synthetic benchmarks evalutation of the CPUs with Geekbench 3.0, which evaluates the CPU both in terms of single-threaded performance and multi-threaded performance.

CPU Benchmarks

In single-threaded applications, Nvidia's custom Denver CPU core takes the first place, followed closely by Apple's enhanced Cyclone core on the Apple A8X. Meanwhile, the older Cortex-A15 and Krait 400 CPU cores are far behind, with the 2.2GHz A15 core in the 32-bit Tegra K1 pulling slightly ahead of the 2.7GHz Krait 450 core in the Snapdragon 805. 

In multi-threaded applications, where all of the CPU's cores can be used, the A8X, with its Triple-core configuration blows past the competition. The dual-core Denver version of the Tegra K1 gets about the same performance as the quad-core Cortex-A15 Tegra K1 variant, with the quad-core Krait 450 coming in last place, but by a very, very small margin. 

Apple's addition of one extra core to the A8X's CPU, together with the fact that Cyclone is a very powerful core, make it easily the fastest CPU in the market for multi-threaded applications. While Nvidia's 64-bit Denver CPU core has some impressive performance, thanks to its wide core architecture, it's core count works against it in the multi-threaded benchmark. It is, in fact, the only dual-core CPU being compared here. Even if it's not as fast as the A8X's CPU, Nvidia's Denver CPU is a beast. Were it in a quad-core configuration, it would absolutely blow the competition out of the water.

The GPU

Moving away from CPU benchmarks, we shall now analyze graphics performance, which is probably even more important than CPU performance, given that it is practically a requirement for high-end tablets to act as a decent gaming machine. First we'll look at OpenGL ES 3.0 performance with GFXBench 3.0's Manhattan test, followed by the T-Rex test, which tests OpenGL ES 2.0 performance, followed by some of GFXBench 3.0's low level tests.

The Manhattan test puts the Apple A8X ahead of the competition, followed closely by both Tegra K1 variants, which have about the same performance, since they have the exact same GPU and clock speed. Unfortunately, the Adreno 420 in the Snpadragon 805 is no match for the A8X and the Tegra K1, something that points out the need for Qualcomm to up their GPU game.

The T-Rex test paints a similar picture, with the A8X slightly ahead of the Tegra K1, while both of the Tegra K1 variants get about the same score, and the Snapdragon 805 falls behind the other two processors by a pretty big margin.

The Fill rate test stresses mostly the processor's memory interface and the GPUs TMUs (Texture Mapping Units). Since both the Apple A8X and the Snapdrgon 805 have the same dual-channel 64-bit LPDDR3 memory interface clocked at 800MHz, the performance advantage the Snapdragon 805 has shown in comparison to the A8X can only be attributed to the possibility that the Adreno 420 GPU has better texturing performance than the PowerVX GXA6850 in the Apple A8X. Meanwhile, the two variants of the Tegra K1 feature the same memory interface, which also consists of a dual-channel 64-bit LPDDR3 interface, only with a lower 533MHz clock speed. Therefore, the Tegra K1 offers signifcantly less texturing performance compared to the A8X and the Snapdragon 805, but is a very worthy performer nevertheless.

The ALU test is more about testing the GPUs sheer compute power. Since Nvidia's Tegra K1 has 192 CUDA cores on its GPU, it naturally takes the top spot here, and by a pretty significant margin.

For some reason, all tests show the 32-bit Tegra K1 in the Nvidia Shield Tablet scoring a few more points than the 64-bit Tegra K1 in the Google Nexus 9. But given that the two processors have the exact same GPU, this difference in performance is probably due to software tweaks in the Shield Tablet's operating system, which would make sense, given that it is more than anything a tablet for gaming.

Thermal Efficiency and Power Consumption

In the ultra-mobile space, power consumption and thermals are the biggest limiting factors for peformance. As the three processors being compared here are all performance beasts, several measures had to be taken so that they wouldn't drain a battery too fast or heat up too much.

In order to keep power consumption and die size in check, Apple has decided to shrink the manufacturing process from 28nm to 20nm, a first in the ultra-mobile processor market. That alone gives it a huge advantage over the competition, since they can put more transistors in the same die area, and with the same power consumption. Since the A8X is, in general, the fastest SoC available, the smaller process node is important to keep the iPad Air 2's battery life good. 

Nvidia's Tegra K1 should also do well in terms of power consumption and thermal efficiency in situations where the GPU isn't pushed too hard. The 28nm HPM process it's built upon is nothing particularly good, but it's still not old for a 2014 processor. While the Kepler architecture is very power efficient, straining a 192-core GPU to its maximum is still going to produce a lot of heat in any case. The Nexus 9 tablet reportedly can get very warm on the back while the tablet is running an intensive game.

Finally, the Snapdragon 805 should be the less power hungry processor because it is also a smartphone processor. Given that a 5" phone can carry this processor without heating up too much or draining the battery too fast, a tablet should certainly be able to do the same. To put things in perspective, if we put the Tegra K1 or the Apple A8X inside a smartphone, both would be too power hungry and would produce too much heat to make for a decent phone. In any case, the Snapdragon 805 is, like the Tegra K1, built on a 28nm HPm process. Given that its not as much a performance moster as the other two processors mentioned here, it must be the least power hungry of all three.

Conclusion

Objectively speaking, the comparisons made here make it pretty much clear that once again Apple takes the crown for the best SoC for this generation of high-end tablet processors. Not that the competition is bad. On the contrary, Nvidia went, in just one generation, from being almost irrelevant in the SoC market (let's face it, the Tegra 4 was not an impressive processor) to being at the heels of the current king of this market (aka Apple). The Tegra K1 is an excellent SoC, and even if it can't quite match the Apple A8X, it's still quite close to it in most aspects.

Meanwhile, Qualcomm is seeing it's dominance in the tablet market start to fail. It's latest SoC, the Snapdragon 805, available even on some smartphones and phablets, is available in only one tablet, while most others carry the Snapdragon 801 or even the 800, and this is disappointing, given that a tablet can utilize the processing power more usefully than a smartphone or a phablet. Either way, the Snapdragon 805 is still a very good processor. It's just far from being the fastest. Perhaps Qualcomm should consider, like Nvidia and Apple, making a processor with extra oomph, but meant only to run inside tablets, because while the Snapdragon 805 is an excellent smartphone processor, it's not as competitive in the tablet market. 

Apple iPad Air vs Microsoft Surface 2: Tablet Comparison

The holiday season is almost upon us, and so the biggest players in the tablet market finally have their latest flagships already available. The iPad Air, from Apple, and Microsoft's Surface 2 are some of the most interesting tablet flagships this holiday season. Considering how Windows RT and the original Surface have both failed to gain significant market share in the tablet market, it'll be interesting to see how the second generation Surface fares. Both tablets have very high-end specs, including high-resolution displays and very powerful processors, along with a high price tag. But which one is worth your money the most?

	Apple iPad Air	Microsoft Surface 2
Body	240 x 169.5 x 7.5mm, 469g (Wi-Fi)/478 (LTE)	275 x 172.5 x 8.9mm, 676g
Display	9.7" IPS LCD 2048 x 1536 (264ppi)	10.6" ClearType TFT LCD 1920 x 1080 (208ppi)
Storage	16/32/64 GB, 1 GB RAM	32/64 GB (microSD expandable), 2 GB RAM
Connectivity	Wi-Fi, GSM (2G), HSDPA (3G), LTE (4G)	Wi-Fi
Camera (Rear)	5 MP with face detection, F/2.4 lens aperture, HDR and 1080p@30fps video	5 MP with LED flash and 1080p@30fps video
Camera (Front)	1.2 MP with face detection and 720p@30fps video	3.5 MP with 1080p@30fps video
OS	iOS 7	Windows 8.1 RT
Processor	Apple A7 (Dual-core Cyclone @ 1.4GHz + PowerVR G6430)	NVIDIA Tegra 4 (Quad-core Cortex-A15 @ 1.7GHz + 72-core ULP GeForce)
Battery	Non-removable Li-Ion 32.4Wh  Usage time: Up to 10hrs	Non-removable Li-Po 31.5Wh  Usage time: Up to 10hrs
Accessories	--	Optional keyboard covers:  - Touch Cover 2 ($119)  - Type Cover 2 ($129)  - Power Cover ($199)
Price	$499 (16 GB, Wi-Fi only)	$449 (32GB)

Design

Build and material quality is absolutely top-notch with these two tablets. The iPad Air has an aluminium unibody frame that's available in either "space" gray or silver. The Surface 2 is encased by silver-colored magnesium, or as Microsoft calls it, VaporMg. But what really sets the Surface 2 apart from all of its competitors is the built-in kickstand at the back, which this time around, stops at two different angles. It's also not very hard to notice that the iPad has some very thin bezels compared to the Surface 2, but that shouldn't really matter that much for most users, unless the looks of your tablet matter a lot to you.  

While in terms of materials the Surface 2 is on par with the iPad, and the kickstand is a very delightful feature, the Surface 2 falls behind severely in terms of dimensions and weight. It's actually not that thick, really. Measuring 8.9mm, it's on par with the ASUS Transformer Pad TF701T and the Lumia 2520, but it's still significantly thicker than the Samsung Galaxy Note 10.1 (2014 Edition) and the iPad Air. The weight is what really bothers me. At 676g, not only is the Surface 2 not significantly lighter than its predecessor, it's also the heaviest tablet we've seen this year. In fact, it's almost as heavy as the first-generation iPad, and is about 200g heavier than the iPad Air. The fact that the Surface 2 has a larger display than its competitors partially justifies the below average weight, and the larger area of the device also means that, due to the weight distribution, the Surface 2 might not feel as heavy as its weight suggests. 

We must, of course consider that the iPad Air and the Surface 2 have completely different purposes. While the iPad air is a device geared towards entertainment, the Surface 2 has productivity written all over it, considering that the official keyboard covers are an essential part of the Surface experience. There are three different keyboard covers available for the Surface 2, all of which attach to the magnetic connector on the tablet's bottom and double as a cover for the tablet's screen. There's the Touch Cover 2, which is 2.75mm thin and whose keyboard has capacitive buttons, not physical ones, and the keys are backlit. I'm not sure how Microsoft managed to put backlighting on such a thin keyboard, but it's very impressive. Then there's the Type Cover 2, which swaps the capacitive buttons for physical ones, thus providing a much better typing experience, but with the trade-off that the thickness increases to 5.4mm. Finally, there's the Power Cover, which is yet to be released, and is just like the Type Cover 2, but adds an integrated battery that extends the tablet's battery life, but it should be considerably thicker than the Type Cover 2. All of the covers provide an excellent typing experience and, together with the inclusion of Microsoft Office 2013 Home and Student, puts the Surface's productivity potential way ahead of the iPad Air. 

Display

The Surface 2 and the iPad Air both feature excellent displays. With the iPad Air it's the usual 9.7" 2048 x 1536 "Retina" display, which is very crisp thanks to its 264ppi pixel density. The use of IPS technology attributes wide viewing angles to the display, and colors are both bright and accurate. The 4:3 aspect ratio of the iPad is great for browsing the web and reading e-books, but is known for causing letterboxing when viewing videos and movies. 

The Surface 2 has a much larger 10.6" display, but unlike its predecessor is suited with a good screen resolution. 1920 x 1080 pixels give the Surface 2 a pixel density of 208ppi, which is obviously less than the iPad Air's 264ppi. Both displays are very sharp, though, and the iPad Air's higher ppi is only significant enough to be slightly noticeable, and is likely to only make a difference when viewing very small text. The display also presents us with wide viewing angles and good color reproduction. The 16:9 aspect ratio of the Surface 2 is great for watching videos, but it does make use in portrait mode almost unbearable, because the screen is too long and too narrow, so keep in mind that you'll want to use the Surface 2 in landscape mode most of the time. 

In terms of sharpness and color reproduction, the two displays are quite close, even though the iPad Air is a tad sharper, but it all comes down to display size and aspect ratio. The Surface 2 displays might be a bit too large for you, and the choice in aspect ratio will depend on what you'll use your tablet for the most. 

Performance

These two tablets are powered by some of the best silicon available currently. With the Surface 2 it's an NVIDIA Tegra 4 processor, which consists of four Cortex-A15 CPU cores with a 1.7GHz clock speed plus a low-power shadow A15 core designed to help keep power consumption low. The Surface 2's high-resolution display is fitted with a large 72-core ULP GeForce GPU. While the Tegra 4's GPU's benchmark scores are decent, the actual architecture the GPU is built on might disappoint you, especially considering it's an NVIDIA GPU. You get 72 discrete shader cores, which separate into 48 pixel shader units and 24 vertex shader units. This discrete pixel and vertex shader architecture was abandoned many years ago in favor of the more efficient unified shader architecture, which all current mobile and PC GPUs use, save for the Tegra 4. But as long as the benchmark scores are good enough, the older architecture won't really affect the user's experience. But, even though it's based on old architecture, the Tegra 4 has a very good GPU and yields some great gaming experience out of the small (but increasing) number of 3D intensive games on the Microsoft Store. Just know that the iPad Air will be a bit smoother most of the time. 

The iPad Air is powered by Apple's latest A7 processor. The A7's CPU consists of two Cyclone cores clocked at 1.4GHz. The Cyclone CPU is a custom ARM CPU designed by Apple, which is the first commercially available mobile CPU based on the ARMv8 64-bit architecture. While 64-bit's benefits lie mostly on larger RAM capacity, which isn't a concern for Apple devices, which are still on the 1 GB range, the architecture's larger memory registers does improve the overall efficiency of the CPU. Not only that, but the Cyclone core is just about the widest mobile CPU ever created, so we can expect to see single-threaded performance that's far ahead of any of its competitors, and is probably why Apple didn't need to go quad-core to keep its SoC offering competitive. The A7 is also fitted with a beefy PowerVR G6430 GPU, which, unlike the Tegra 4, is the pinnacle of contemporary mobile GPU architecture, with OpenGL ES 3.0 support and a unified shader architecture. So aside from the A7's higher benchmark scores compared to the Tegra 4, the A7 also has more potential for future-proofing.

But since babbling about architectures probably doesn't matter to you, let's get to the benchmarks. First up is Geekbench 3, which measures CPU and memory speed. Note that since the Geekbench 3 app isn't available for Windows RT, I had to use the results from the closest match to the Surface 2 I could find running Android: The 1.9GHz Tegra 4-powered ASUS Transformer Pad. Since the clock speed here is 200MHz higher than on the Surface 2, keep in mind that the Surface 2's performance should be lower, however, since I'm comparing devices from completely different OSes, the difference between the Surface 2 and the Transformer Pad results I used here might account for more than just the 200MHz clock speed difference. Don't expect a huge performance gap between the two Tegra 4 devices, though.

This chart illustrates how the A7 has much better single-threaded performance compared to its rivals, and how that allows the SoC to offer competitive multi-threaded performance with half the core count of its competitors and a much lower clock speed. The A7 actually even beats the Transformer Pad (and probably beats the Surface 2 by a slightly larger margin) in multi-threaded performance, but not by much. It's a bit more complex than that though. It's still true that the Surface 2 has double the thread count compared to the A7, so it should be noted that, while having strong single-threaded performance is more important for overall performance, having more threads is better for things like multi-tasking, something that, coincidentally, is an important aspect of the Surface 2's productivity potential. 

 Moving on to graphics tests, the Surface 2's results don't look so good. The Surface 2 is actually one of the slowest Tegra 4 implementations available, maybe because of the OS it runs on, or maybe because the graphics clock is reduced along with the CPU core. The iPad Air, along with Samsung and Qualcomm's latest offerings, trumps the Surface 2 in this test. In fact, the Surface 2's performance in this specific test is almost identical to the iPad 4.

Moving on to the Onscreen T-Rex HD test, which is run on the devices' native resolutions, we see the iPad Air's higher pixel count holding it back, so that the 1080p Samsung Galaxy Note III outperforms it. Even though it has to power approximately 700 thousand more pixels than the Surface 2, the iPad Air still manages to beat it by a moderately large margin.

The lighter Egypt HD test now causes the Surface 2 to fall way behind all of its competitors, while the iPad Air sits comfortably between the Snapdragon 800 and the Exynos 5420.

Finally, the Egypt HD test run on native resolution shows the iPad Air once again falling behind the Note IIIs slightly, but still far ahead of the Surface 2.

Microsoft clearly doesn't care as much about gaming performance as Apple, otherwise they would've worked on optimizing the OS for its processor a bit better to at least yield benchmark scores that are close to other Tegra 4 implementations on Android. Then again, given that the Surface 2 is more of a working device than a playing device, I can understand why Microsoft wasn't too concerned about the GPU. 

Power Consumption

It's a bit strange that the iPad Air is so much thinner and lighter than the Surface 2 and yet has a bigger battery. The latest iPad comes with a 32.4Wh battery, which is slightly larger than Surface 2's 31.5Wh battery. Both are very large batteries, and should keep these devices running for quite some time on a single charge. However, the iPad Air does have more pixels to power, which increases overall power consumption compared to the Surface 2. As for how much power the SoC draws, both tablets have processors built on 28nm circuitry. The A7 has less CPU cores to power versus the Tegra 4, but the T4's shadow A15 core saves it in that regard. When running intensive tasks, however, the Dual-core Cyclones are likely to draw less power than the Quad-core A15s. Anyways, both Microsoft and Apple claim the same 10 hour battery life.

Conclusion

It's actually very easy to choose whether the Surface 2 or the iPad Air is better for you. If you want a tablet that offers the best productivity in the tablet market, pick the Surface 2. On the entertainment side Microsoft is making strides with Windows RT, as the 8.1 update improves the OS significantly and the Windows Store is improving on a daily basis, and with decent gaming performance and a bright, sharp display, the Surface 2 is not bad at all for entertainment, but the iPad Air is certainly better on this front. With almost unmatched gaming performance and one of the best displays in the mobile market, as well as what is just about the best app selection in existence, the iPad Air tackles your entertainment needs with near perfection. Of course, if you're fine with third-party bluetooth keyboards, the iPad Air, with its iWork app suite, also can also be used for productivity. While not as good as Microsoft's keyboard Covers, the third-party iPad keyboards are decent alternatives.

There's also the pricing factor. The Surface 2 undercuts the iPad Air with a starting price of $449 for 32 GB of storage, compared to the iPad Air, which sells for $499 with 16 GB of storage (Note: Windows 8.1 RT takes quite a lot of space out of the Surface 2's 32 GB capacity, and with Office included you'll only have about 15/16 GB available). The pricing is still similar though, and it'll almost definitely come down to whether you want a device for work or for entertainment.

Apple iPad Air vs ASUS Transformer Pad TF701T: Tablet Comparison

The holiday season is almost upon us, and so the biggest players in the tablet market finally have their latest flagships already available. The iPad Air, from Apple, and the Transformer Pad TF701T, from ASUS, are some of the most interesting tablet flagships this holiday season. Both of them have very high-end specs, including high-resolution displays and very powerful processors, along with a high price tag. But which one is worth your money the most?

	Apple iPad Air	ASUS Transformer Pad
Body	240 x 169.5 x 7.5mm, 469g (Wi-Fi)/478g (LTE)	263 x 181 x 8.9mm, 585g
Display	9.7" IPS LCD 2048 x 1536 (264ppi)	10.1" IPS LCD 2560 x 1600 (299ppi)
Storage	16/32/64 GB, 1 GB RAM	32/64 GB (microSD expandable), 2GB RAM
Connectivity	Wi-Fi, GSM (2G), HSDPA (3G), LTE (4G)	Wi-Fi
Camera (Rear)	5 MP with F/2.4 aperture, face detection, HDR and 1080p@30fps video	5 MP with 1080p@30fps video
Camera (Front)	1.2 MP with face detection and 720p@30fps video	1.2 MP with 720p@30fps video
OS	iOS 7	Android 4.3 Jelly Bean
Processor	Apple A7 (Dual-core Cyclone @ 1.4GHz + PowerVR G6430 @ 450MHz GPU)	NVIDIA Tegra 4 T40X (Quad-core Cortex-A15 @ 1.9GHz + 72-core ULP GeForce)
Battery	Li-Po 32.4 Wh	Li-Po 31 Wh
Accessories	--	- Keyboard dock
Starting Price	$499 (16GB)	$449 (32GB)

Design

The iPad and Transformer lines of tablets have had the most distinguished tablet designs for a long time, and the trend continues with the TF701T and the iPad Air. Unfortunately though, the TF701T has fallen behind the competition in terms of size and weight. While 2013 has ushered in a new trend of thinner and lighter tablets with narrower bezels, the Transformer tablet is still about as thin as light as its predecessors, and the bezel continues to be as wide as it can get. Of course, the unchanged bezel width is a design choice, rather than a technological incapacity to reduce it, and it at least brings the benefit of having lots of room where you can rest your thumbs without them touching the screen. 

The Transformer Pad is noticeably thicker than the iPad Air (8.9mm vs 7.5mm), but the Transformer Pad isn't exactly thick either, as it's at least slightly thinner than last year's iPad 4. The TF701T is also much heavier, weighing 585g, versus the iPad Air's 469g. Again, that doesn't mean that the TF701T is too heavy, and it's significantly lighter than the iPad 4, but it's undeniable that the iPad Air's lighter body makes it less tiring to hold and use for extended periods of time compared to the Transformer Pad. 

The Transformer Pad and the iPad Air are among the few tablets that have an aluminium construction, so they're on the same page in terms of the quality of its materials. The iPad Air, adopting the same design as the iPad mini, has an aluminium back, available in two colors: 'Space' gray and silver. The Transformer Pad also has a gray-colored aluminium back, but with a finish of concentric circles, a signature ASUS design. Like the LTE version of the iPad Air, the Transformer Pad has a plastic RF strip on the top.

Display

The iPad Air and the ASUS Transformer Pad have some of the best displays ever seen on a tablet. Both have extremely high resolutions, both get pretty bright and colors look vivid on both. 

The iPad Air has the usual 9.7" IPS display, and has a resolution of 2048 x 1536, resulting in a pixel density of 264ppi, so as expected text is razor sharp. The IPS technology also ensures a near 178-degree viewing angle and bright colors. The 4:3 aspect ratio of the display is very good for reading and web browsing, but isn't so great for watching videos because the 16:9 aspect ratio of most movies and videos result in a lot of letterboxing in the iPad's 4:3 screen. 

The Transformer Pad has a 10.1" IPS display with power-efficient IGZO technology manufactured by Sharp, with a 2560 x 1600 resolution. This resolution gives the tablet a 299ppi pixel density. While you may think that 299ppi is much sharper than 264ppi, the difference in sharpness between the two screens is barely noticeable, at least at normal viewing distances. Much like the iPad Air, the TF701T's use of IPS display technology gives it wide viewing angles and nicely saturated colors. The 16:10 aspect ratio of the Transformer Pad's screen is great for watching movies, but it makes use in portrait mode a bit awkward. 

And let's not forget about what gives the Transformer Pad its name. While the iPad Air is almost definitely a device geared towards entertainment rather than productivity, the Transformer Pad goes the other way. That's because the Transformer Pad is actually a hybrid tablet/notebook. The optional keyboard dock that ASUS sells for about $149 attaches to the tablet via the dock connector at the bottom and turns the Transformer Pad into a sort of 10.1in Android notebook. The presence of a physical keyboard obviously makes writing documents a lot easier than using onscreen keyboards, and the device's small footprint makes it very portable, so if you're into writing documents while on the go, the Transformer Pad is perfect for you.

The keyboard itself isn't very different from previous iterations. This time around it's made of plastic, unlike the aluminum-built tablet. The dock doesn't look super sturdy, but I don't expect it to break very easily, however, when docked the tablet has a bit too much space to wobble, which is a bit of a concern to me. In fact, I've been seeing many complaints that some of the first units manufactured had some problems with the tablet-to-dock connection, so be aware of that. Other changes include a USB 3.0 port (up from USB 2.0 in the last generation). The keyboard dock also features a 16Wh battery that charges the tablet's battery when docked, giving it a little extra juice on a single charge.

Performance

As flagship tablets, both the iPad Air and the Transformer Pad feature top of the line processors. The iPad Air is powered by an Apple A7 processor, while the Transformer Pad sports an NVIDIA Tegra 4 SoC. 

The Apple A7 is a remarkable processor, in the sense that it's CPU core, dubbed Cyclone, is the first to be based on the ARMv8 architecture, which also happens to be the first mobile 64-bit architecture. While the main advantage of 64-bit is support for more than 4GB of RAM, an advantage that won't be useful for iOS devices for a long time, since they're still on 1GB, the 64-bit architecture also boosts the CPU's performance because it can handle much larger memory addresses than conventional 32-bit CPUs. That alone boosts single-threaded performance significantly. Not only that, but Apple's Cyclone core is also much wider than its predecessor, the Swift. In fact, it's the widest mobile CPU architecture ever seen so far. The wider machine plus the 64-bit architecture boost single-threaded performance ahead of all of its competitors. With so much power on a single core, the A7 needs only two of these Cyclone cores clocked at 1.4GHz to be competitive with the latest quad-cores.

The Tegra 4's CPU is a bit more mundane than the A7's, but it still performs admirably well. It has four Cortex-A15 cores clocked at 1.9GHz, plus a shadow A15 core that can go all the way to 825MHz. This is the same 4-PLUS-1 architecture seen on last year's Tegra 3, and is quite similar in function to ARM's big.LITTLE technology. Basically, in situations where the performance demand from the CPU is low, for example, when your device is locked or idling, the quad-core A15 is power gated and all processing is transfered to the shadow A15, which consumes much less power than the other A15 cores. When the demand on the CPU increases beyond the shadow A15's capabilities, the processing transfers back to the quad-core A15 seamlessly. The only function of this architecture is to increase battery life. 

Looking at the GeekBench 3 results for the Apple A7 and the Tegra 4, it's clear that the A7 is much ahead of its competition in single-threaded performance. However, moving to multi-threaded applications, the A7 has the disadvantage of having less cores than its competitors, but it can still achieve a score close to its quad-core competitors. 

In theory, the Apple A7 really is on par with the Tegra 4 and the other high-end SoCs, but the A7 may have the upper hand due to its strong single-threaded performance. Mobile OSes and most of the applications available for them usually rely more on single-threaded performance, so in this sense the A7 may turn out to be faster for most uses than its competitors. However, having more cores = more threads, so the A7's quad-core competitors may be better for multitasking, something that OEMs have been craving to perfect on tablets. But as far as theory goes, the Apple A7 is just as good as the Tegra 4. 

Moving on to the GPU, the A7 continues Apple's tradition of licensing GPUs from ImgTech, and this time it's the PowerVR G6430. This is a very powerful GPU that boasts of OpenGL ES 3.0 support.

As you may have imagined, the Tegra 4 features NVIDIA's own GPU core, which they like to call the 72-core ULP GeForce. Unfortunately, the Tegra 4 uses an ancient shader architecture, which is composed of discrete pixel and vertex shaders, a much more limited architecture compared to the unified shader architecture in the PowerVR G6430. The Tegra 4 also does not support OpenGL ES 3.0, and only goes as far as OpenGL ES 2.0. For now, this is not a problem as there aren't any games that require OpenGL ES 3.0, but in a year or two it may be. 

To see how these two tablets compete in terms of GPU performance we turn to GFXBench. Note that the first two tests are rendered offscreen at a fixed 1080p resolution, so the Transformer Pad's higher resolution doesn't penalize it there.

While the iPad Air reigns supreme in the T-Rex HD Offscreen test, the Transformer Pad is left as the slowest flagship tablet this holiday season. The difference in framerate between the two tablets isn't enormous, but it's still a very tangible difference. 

Once again, there is quite a gap between the Transformer Pad and the iPad Air here.

Next up are the Onscreen tests, which are run at the device's native resolution. The Transformer Pad really falters here because it has to render at a higher resolution than the iPad Air. Also, the Onscreen tests are the most representative of real-world graphics performance.

The Transformer Pad's higher resolution increases the gap between it and the iPad Air quite tangibly.

Now the Transformer Pad is way below its main competitors, even the Galaxy Note 10.1, which has the same screen resolution. The difference in performance between the iPad Air and the Transformer Pad are pretty big here.

<geek talk> I suspect that the Transformer Pad falters so badly in the Egypt HD Onscreen test because of its fill rate limitations. Since the Egypt HD test is less shader bound than the T-Rex HD test and is therefore probably more fill rate bound, and the Tegra 4 in the Transformer Pad is tasked with powering A LOT of pixels, together with the Tegra 4's average fill rate score, I think it's probable that what we're seeing here is a performance bottleneck due to having few ROPs in the Tegra 4's GPU die. </geek talk>

Power Consumption

As flagship tablets that pack a lot of punch, the iPad Air and the Transformer Pad are expected to have relatively high power consumption. The high-resolution displays themselves draw a lot of power, and when at full power the tablets' processors should be power hungry as well, however, since the processors are both based on 28nm technology it shouldn't be a huge concern. The Tegra 4's 4-PLUS-1 architecture helps the Transformer Pad last a little longer on a single charge, too. 

Both tablets have large batteries to sustain their power hungry systems, and on the Transformer Pad it's a 31Wh unit, slightly smaller than the iPad Air's 32.4Wh battery (So yeah, the Transformer Pad is thicker AND has a smaller battery. Come on ASUS). And the iPad Air does in fact last considerably longer on a single charge than the Transformer Pad. However, don't forget that the Transformer's keyboard dock has a 16Wh battery that can give the Transformer Pad up to 4 hours of extra usage. With the keyboard dock, the Transformer Pad can outlast the iPad Air quite easily. 

Conclusion

Many times I call a tie in these comparisons, but this time I have to say that for most uses the iPad Air is clearly the better tablet. It has a much sleeker, lighter frame, significantly better performance and even better battery life than the Transformer Pad TF701T. Of course, if you want to have a tablet on which you can be productive, then that changes everything. The iPad Air is simply not a very good device for work. Of course you can always use a third-party bluetooth keyboard with iWork apps and call the iPad productive, but ASUS' integration of the keyboard dock and the tablet/notebook convertible concept makes the Transformer offering better for productivity than any iPad + bluetooth keyboard combination. If. however, you only want a tablet for playing games, watching movies, browsing the web, etc., then the iPad Air is probably a better offering than the Transformer Pad.

In truth, the Transformer Pad would've been much better had it launched a few months earlier. It's much more of a close match to the iPad 4 rather than the iPad Air, so basically the Transformer Pad is a tablet that feels one generation old. 

However, I can't just say that the iPad Air is superior to the Transformer Pad and leave it at that, as these two are competing at very different price points. The 32GB Transformer Pad costs $449, $150 less than the 32GB iPad Air ($599), and even the entry-level 16GB iPad Air ($499) costs $50 more. The Transformer Pad with the keyboard dock would match the price of the iPad Air at the same storage capacity, actually. Compared to other offerings in the $449 price range, the Transformer Pad fares much better, competing with the Surface 2 and the Xperia Tablet Z.

So who would I recommend the ASUS Transformer Pad to? Obviously, I highly recommend it for who likes to work while on the go. If the iPad Air's $499 starting price is a bit too much for you, the Transformer Pad is generally the best tablet in the $449 range. However, if you want a tablet for entertainment rather than productivity, or if can do with bluetooth keyboards for the iPad and you can afford $499 the iPad Air is almost definitely the better tablet.

Apple iPad Air vs Samsung Galaxy Note 10.1 (2014 Edition): Tablet Comparison

The holiday season is almost upon us, and so the biggest players in the tablet market finally have their latest flagships already available. The iPad Air, from Apple, and the Galaxy Note 10.1 2014 Edition, by Samsung, are some of the most interesting tablet flagships this holiday season. Both of them have very high-end specs, including high-resolution displays and very powerful processors, along with a (perhaps too) high price tag. But which one is worth your money the most?

	Apple iPad Air	Samsung Galaxy Note 10.1 (2014)
Body	240 x 169.5 x 7.5mm, 469g (Wi-Fi)/478g (LTE)	243 x 171 x 7.9mm, 540g (Wi-Fi)/547g (LTE)
Display	9.7" IPS LCD 2048 x 1536 (264ppi)	10.1" TFT LCD 2560 x 1600 (299ppi)
Storage	16/32/64 GB, 1 GB RAM	16/32 GB, 3 GB RAM
Connectivity	Wi-Fi, GSM (2G), HSDPA (3G), LTE (4G)	Wi-Fi, GSM (2G), HSDPA (3G), LTE (4G)
Camera (Rear)	5 MP with 1080p@30fps video, F/2.4 aperture, HDR, face detection	8 MP with LED flash, face detection and 1080p@60fps video
Camera (Front)	1.2 MP with 720p@30fps video and face detection	2 MP with 1080p@30fps video
OS	iOS 7	Android 4.3 Jelly Bean
Processor	Apple A7 (Dual-core Cyclone @ 1.4GHz + PowerVR G6430 @ 450MHz)	-Wi-Fi: Exynos 5420 (Quad-core Cortex-A15 @ 1.9GHz + Quad-core Cortex-A7 @ 1.3GHz + Mali-T628) -LTE: Qualcomm Snapdragon 800 MSM8974 (Quad-core Krait 400 @ 2.3GHz + Adreno 330 @ 450MHz)
Battery	Non-removable Li-Po 8,820 mAh Video playback time: 10hrs	Non-removable Li-Po 8,220 mAh Video playback time: 10hrs
Starting  Price	$499 (16GB, Wi-Fi)	$549 (16GB, Wi-Fi)
Accessories	--	S Pen

Design

Both Samsung and Apple have produced good designs for their flagship tablets, but it'll come down to the usual plastic vs aluminium debate, or in this case faux leather vs aluminium. While the iPad Air maintains its all-aluminium design, this time inspired on the iPad mini rather than the previous iPad, Samsung has done the same as it did with the Note III, replacing glossy plastic with a back casing that is still plastic, but is now disguised as leather. I'm not sure I appreciate the faux leather design at all. Personally, not only do I prefer the iPad's aluminium construction, but I think the faux leather looks so old-fashioned that even the glossy plastic they used previously may look better. That's just my opinion though, and ultimately it'll come down to personal taste. At least the faux leather gives the Galaxy Note 10.1 more grip than the iPad Air. The Galaxy Note 10.1 is available in black and white (bezel color included), and the iPad Air is similarly available in "Space" gray and silver. 

Both the Galaxy Note 10.1 and the iPad Air are remarkably thin and light. They are in fact one of the thinnest and lightest tablets available, but the iPad Air is definitely the winner in this department. It's technically thinner than the Note 10.1 (7.5mm vs 7.9mm), but the difference is so small it's practically unnoticeable to the user. While their thickness is one the same level, the iPad Air is significantly lighter than the Note 10.1 (469g vs 540g). In this case the difference in weight is definitely noticeable. The Note 10.1 is still lighter than most other tablets, though. 

Display

The display is possibly the area where these two tablets fare the best. Both are large, crisp, bright, and colorful. The iPad Air, much like two of its predecessors, has a 9.7" display with a 4:3 aspect ratio and a resolution of 2048 x 1536, which gives the screen 264ppi pixel density. The Note 10.1 has, like the name implies, a 10.1" display with a 16:10 aspect ratio that packs 2560 x 1600 pixels and has a pixel density of 299ppi.

Perhaps the most fundamental difference between the displays is the aspect ratio. The almost-square 4:3 display in the iPad Air makes it better to use in portrait mode, and is more suited for reading and web browsing, while the wide 16:10 display in the Note 10.1 makes it better suited for usage in landscape mode, and frankly makes portrait mode use a bit awkward, but is generally better for watching videos. 

You may think that the difference between 264ppi and 299ppi is huge, but honestly, it's hard to notice the Galaxy Note 10.1 being any crisper than the iPad Air, especially at the usual viewing distance. The difference is there, however, and any eagle-eyed person would probably notice a slight difference in sharpness. 

Leaving the numbers and quantitative data aside, both the Note 10.1's and the iPad Air's displays are sufficiently bright. Viewing angles are good, as is expected of any half-decent tablet these days, and colors are accurate and satisfyingly saturated in both tablets. 

Performance

Both of these tablets have the most powerful processors available to handle their ultra high-resolution duties. On the iPad Air we have the same A7 SoC found in the iPhone 5s and the Retina iPad mini, and on the Galaxy Note 10.1 we have either the Snapdragon 800 or a rare Exynos 5 Octa (5420) SoC for the LTE and Wi-FI models, respectively. All of these SoCs are built on 28nm process node to keep power consumption lower. 

The A7's CPU technology has gained quite a bit of popularity since its launch back in September. That's because its the first CPU to utilize the ARMv8 ISA, which happens to be a 64-bit architecture, hence also making it the first 64-bit mobile SoC. Apart from the new ISA, Apple made its new Cyclone CPU core the widest mobile CPU ever seen. With all that power packed into a single core, Apple needed no more than two of those cores with a relatively low 1.4GHz clock speed to match its competitors' performance. As benchmarks show, the dual-core Cyclone CPU @ 1.4GHz is perfectly capable of competing with the latest quad-core beasts, and since it packs much more power on a single core, the A7 really stands out from its competitors in single-threaded CPU benchmarks.

The CPU in the Exynos 5420 SoC in the Wi-Fi Galaxy Note 10.1 is one of the few CPUs to ultilize ARM's big.LITTLE technology. Based on the ARMv7 32-bit ISA, the Exynos 5420 contains two CPU clusters, one high-performance cluster to handle demanding tasks, and a low-power cluster for handling lighter tasks while reducing power consumption.The high-performance cluster contains four Cortex-A15 cores clocked at 1.9GHz, while the low-power cluster has four Cortex-A7 cores @ 1.3GHz. 

The Qualcomm Snapdragon 800 variant of the Galaxy Note 10.1 (the LTE version) has, like Apple, a custom CPU core dubbed Krait 400, based on the ARMv7 32-bit ISA. The Snapdragon 800 has four Krait 400 cores with an insane 2.3GHz clock speed. 

Like I said before, since the A7's Cyclone CPU has a 64-bit architecture and is wider than all of its competitors, it manages a much higher score in single-threaded CPU benchmarks. However, in multi-threaded applications the A7 has the disadvantage of having fewer cores compared to its competitors, however it can still definitely keep up with its quad-core competition. The multi-threaded test puts the A7 very close to the Exynos 5420, but both processors lag behind the Snapdragon 800.

With the CPU out of the way, let's focus on the GPU of the Galaxy Note 10.1 and the iPad Air. The A7 SoC follows Apple's tradition of licensing GPUs only from ImgTech, and so we have a PowerVR G6430 graphics processor in the A7. On the Wi-Fi Note 10.1's Exynos 5420 processor there's an ARM Mali-T628 GPU, and the LTE Note 10.1 has an Adreno 330 GPU. All of these GPUs are among the most powerful mobile GPUs available, so we turn to GFXBench to tell us which of these GPUs is the most powerful.

Note: Unfortunately there are no benchmark scores yet available for the Snapdragon 800-based Note 10.1, so I'm taking data from the closest match I could find, the Galaxy Note III with Snapdragon 800. However, I'll omit the Note III scores from the Onscreen tests due to the difference in resolution between the Note III and the Note 10.1.

The T-Rex HD Offscreen test shows the PowerVR G6430 in the iPad Air remarkably close to the Adreno 330, however the Mali-T628 GPU in the Wi-Fi Note 10.1 lags behind them both, but at least outperforms the NVIDIA Tegra 4 SoC in the ASUS Transformer Pad.

The lighter Egypt HD Offscreen test shows the iPad Air's GPU falling behing both the Wi-Fi Galaxy Note 10.1 and the Snapdragon 800-powered Galaxy Note III and puts the Snapdragon 800 at the top of the chart.

Note that since these two tests are rendered at a fixed, non-native resolution, the difference between the resolution of the Note 10.1 and the iPad Air don't affect the scores here. 

The Onscreen tests illustrate how the 1 million more pixels that these two Android flagships have to push versus the iPad Air bog down their performance. The T-Rex HD test shows that the iPad Air managed a much higher score compared to the Exynos-based Galaxy Note 10.1 and the Tegra 4 ASUS Transformer Pad TF701T. 

Since the Egypt HD test is much lighter than T-Rex HD the margin between the iPad Air and its competitors becomes narrower. However, it's still clear that the iPad Air, due to its significantly lower resolution, can push more frames than its 1600p Android competitors. 

Until the Snapdragon 800-based LTE Galaxy Note 10.1 gets released there's no data to indicate how it compares to the iPad Air in the Onscreen tests, although if I were to guess, I'd say that, even though the Adreno 330 is slightly more powerful than the PowerVR G6430 in the Apple A7, its performance advantage still won't be able to offset the resolution difference between it and the iPad Air.

Usually, the Onscreen tests would mimic most accurately real world gaming performance, given that Android and iOS games tend to run at the device's native screen resolution, but since the iPad 3 developers have been going another way: For specific ultra high-res devices, in order to avoid performance issues, the game runs at a lower-than-native resolution and then upscales to the device's screen resolution.  For example, a developer might program a game to run at 1920 x 1200 and then scale to 2560 x 1600 on the Galaxy Note 10.1 to keep framerates high. Given how the Galaxy Note 10.1's higher resolution obviously puts it behind its iPad competitor, it might be necessary for this sort of optimization to be made to keep a decent framerate in very demanding 3D games.

Conclusion

The Galaxy Note 10.1 and the iPad Air are in fact similar in many ways. They both have thin, light designs (although the plastic vs metal war continues with these flagships), displays with a very high resolution, large batteries and some of the best-performing SoCs available. 

In hardware terms, the iPad Air and the Galaxy Note 10.1 2014 Edition are indeed very similar, so it'll probably come down to software to determine which one is best for you. With the Note 10.1, we have Android 4.3 (and soon enough 4.4) with Samsung's TouchWiz UI added on top, and the iPad Air obviously runs iOS 7. 

The addition of the S Pen digitizer might make you choose the Note 10.1 over the iPad Air, but that'll be only if you really value the advantages that a stylus brings.

Selling for the usual $499 for the 16GB Wi-Fi version, the iPad Air is an expensive tablet, although not as expensive as the Galaxy Note 10.1, which sells for $549 for the 16GB Wi-Fi version. $549 is asking for a lot, so unless the S Pen is really useful for you or you really prefer the Android ecosystem, the iPad Air offers more bang for your buck than the Galaxy Note 10.1 2014 Edition.