For this comparison, note that the Galaxy Book comes in two sizes – one with a 10-inch display and another with a 12-inch display. These differ in size as well as configuration. The Microsoft Surface Pro 4 only comes in one 12-inch size.
2-in-1 tablet/laptops come in several form factors. These are both tablets first, which can be used with or without their fully detachable keyboards.
The smaller Galaxy Book is the outlier here; the larger Galaxy Book and Surface Pro 4 have very similar dimensions.
If you're worrying about weighing down your bag, the smaller Galaxy Book is your best bet. If you want a 12-inch display, the Samsung option is still a better choice, but just barely. It weighs about 2-percent less than the lightest Surface Pro 4.
Note that these weights do not include the keyboard accessory.
Both makers opt for metal builds.
There's only one silver option for the Surface Pro 4. Samsung has made the Galaxy Book in silver and black, but has not confirmed whether both of these will be available on the US market.
The 12.3-inch Surface Pro packs in 5-percent more screen space than the comparably sized Galaxy Book.
The Surface Pro 4 has the highest display resolution, but to be fair, the Galaxy Books' displays impressed us during the hands-on time we've had with them so far.
Both machines offer active stylus support. Samsung's S Pen (which does not require charging or a battery) is bundled with the tablet. The Surface Pro supports Microsoft's Surface Pen, which requires one AAAA battery. Most purchasing options for the Surface Pro include the stylus, but Microsoft recently started shipping a version of the entry-level (Core m3) SP4 that doesn't include the pen.
Being tablets first, both of these machines have touchscreens.
Keyboard attachment included
Samsung does buyers a favor and bundles the optional keyboard accessory with the device. Surface Pro 4 users must buy the Type Cover separately. It starts at US$130.
The smaller Galaxy Book only has a front-facing camera, which should be fine for Skype and selfies. The two 12-inch devices have both front and rear-facing cameras, but Samsung has the sharper rear camera.
The Surface Pro 4 is not available with standalone cellular, so you'll have to rely on Wi-Fi to get your internet fix. Both Galaxy Books are available in Wi-Fi only or Wi-Fi + LTE models.
The Galaxy Books have one generation-newer Intel core processors, but the Surface Pro 4 has an Intel core i7 processor option which is not available in the Samsung machines.
The 10-inch Galaxy Book has one 4 GB memory option. The 12-inch Galaxy Book adds an 8 GB size; the Surface Pro has 4 GB, 8GB and 16 GB options.
The smaller Galaxy Book starts off with a mere 64 GB of storage, but there's a 128 GB option as well. The 12-inch Galaxy Book with 8 GB of RAM also has 256 GB of storage. The Surface Pro has four built-in storage levels ranging from 128 GB to a capacious 1 TB.
Both Samsung and Microsoft allow for expandable storage via microSD.
These are manufacturers' estimates, which are subject to skepticism and variation, but the 12-inch Galaxy Book seems to have the longest life.
The Samsung 2-in-1s have newer USB Type C ports – one for the 10-incher, and two on the 12-incher. The Surface Pro has one USB port with the older USB 3.0 standard, but it also has a mini DisplayPort.
The Surface Pro 4 supports facial recognition through Windows Hello, so you can login just by showing your face. You can also opt for an upgraded Type Cover with a fingerprint sensor built in.
The Galaxy Book does not have any biometric sensors built into the device, but it does have Samsung Flow app which facilitates connectivity and file sharing between devices. If you have a Galaxy phone, you can unlock the tablet using the fingerprint scanner on the paired phone.
No mobile software here – both machines run full desktop versions of Windows 10.
Samsung has not confirmed a release date for the Galaxy Book. Meanwhile, the Surface Pro 4 is due for an upgrade – it's been around since October 2015.
We're still waiting for a price point on the Samsung Galaxy Book, but we expect it to be priced comparably to the Surface Pro, considering how similar the two devices are.
Since the Surface Pro 4 is now over a year old, its price has dropped. It originally retailed starting at $1,029 for both the entry-level tablet and keyboard accessory combined. Nowadays, the set is available directly from Microsoft starting at $799 (for the tablet) plus $130 for the basic Type Cover, though it's likely possible to find it elsewhere cheaper.
We wouldn't be surprised if Microsoft unveils a new generation of the Surface Pro on or around the time Samsung confirms price and release date. If some (unconfirmed) rumors are to be believed, the Surface Pro 5 (or its equivalent) will be unveiled in the coming months.