The iPad Pro is a huge tablet that you can attach a keyboard accessory (sold separately) to, in order to turn it into a faux laptop.
Sizes are pretty close, with the Surface Book measuring 5 percent taller and 2 percent wider.The Surface Book is much thicker, but keep in mind that this measurement includes its screen folded over on top of its keyboard. The iPad's thickness is for the tablet only.
In Clipboard mode (screen only), we measured our Surface Book review unit at 7.14 mm thick – or just 3 percent thicker than the iPad Pro.
In tablet mode, weights are very close, but the Surface Book adds much more heft once you dock it onto its keyboard base.
Both machines have premium, all-metal bodies.
The iPad Pro should make for a better faux laptop than any previous iPad, but it still earns the "faux" moniker, as its keyboard doesn't have a trackpad. For that matter, iOS doesn't even support mouse input of any kind.
The Surface Book includes Microsoft's latest version of the Surface Pen, while Apple will sell its "Pencil" separately.
The Surface Book is only sold in one silver color option, while Apple has three iPad Pro colors up for grabs.
The Surface Book's screen is 5 percent bigger than the iPad Pro's. Both are much bigger than more traditional tablets in the 10-inch range, like the iPad Air 2.
Resolutions are similar, and dense enough that both devices will still look sharp even in tablet mode (where they'll sit closer to your eyes).
The App Store has come a long way in terms of productivity apps, but if you want the iPad Pro to replace your laptop, keep in mind that you'll be more limited than on a machine that runs full desktop software.
That means all iPad Pro apps are sandboxed and come from the App store, there's no direct access to the file system and you can't make any command-level tweaks. It's app-centric and cloud-centric: the world Apple has devoted the last decade to pushing us into (with considerable success).
Starting in iOS 9, Apple's mobile OS joins Windows in supporting two apps running side-by-side.
Facial recognition login
Microsoft's new Surfaces have Windows Hello-friendly cameras that let you securely log into your machine just by sitting down in front of it. It's super-fast, and the easiest password replacement yet.
That last category voids the need for a fingerprint sensor on the Surface, but Apple's Touch ID gives you a similar quick login option on the iPad Pro.
Touch ID also has the added bonus of working with some third-party apps and extensions, like password managers and note-taking apps.
We haven't yet seen any benchmarks for the iPad Pro's A9X, but the standard A9 chip that it's a variant of (found in the iPhones 6s and 6s Plus) scores about 20 percent slower (single core) or 33 percent slower (multi core) in Geekbench 3 compared to the entry-level Core i5 Surface Book.
Apple hasn't officially announced this, but signs are pointing to 4 GB of RAM for the iPad Pro.
The iPad's GPU is part of its A9X system on a chip, while the Surface Book gives you integrated Intel graphics in all models, with the bonus of a discrete Nvidia graphics card (stashed away in the keyboard) in some of the more expensive models.
The Surface Book has two batteries. Since only the smaller one lives inside its screen, its tablet mode is only good for an hour or two of standalone uptime per charge (at least if you have the brightness cranked up).
This is the single biggest reason that tablet mode is more of a secondary way of using the Surface Book.
The Surface Book has two USB 3.0 ports.
In terms of internal storage, the entry-level Surface Book matches the max-level iPad Pro at 128 GB.
The Surface Book also has an SD card slot.
The Surface Book's Mini DisplayPort can mirror the laptop's display on a TV or external monitor. You can achieve a similar setup with the iPad Pro's Lightning port, but you'll need an adapter.
There's no cellular Surface Book, but you can buy the 128 GB iPad Pro in an LTE variant.
We don't see many people using either device for much photography, but they do both have 8 MP shooters on the rear.
The new Surfaces launched in October (though the Surface Book has been back-ordered since launch), while the iPad Pro should be launching soon.
Even after adding Apple's keyboard and Pencil accessories, the Surface Book starts at US$432 more expensive.
Keep in mind, though, that the entry-level iPad Pro only gives you 32 GB storage with no way to expand that after the fact. For the 128 GB iPad Pro, the one that's equivalent to the entry-level Surface, the iPad Pro (with accessories) gets a little closer, at $282 cheaper.
We'll have more on the iPad Pro soon. You can read Gizmag's Surface Book review right now.