As you can see, the Moto Z is the bigger phone, coming out 5 percent taller and 4 percent wider.
Technically the HTC 10 is 73 percent thicker, but there are a couple caveats. First, the Moto Z is only measured without any of its modular shells attached (they're basically the whole point of buying the phone) and that also doesn't measure its protruding camera hump. The HTC 10, meanwhile, has a rounded back and its beefy measurement is a little deceiving since it only includes the thickest point.
... so while the Moto Z is indeed an insanely thin phone, and the HTC 10 clearly isn't hanging its hat on that spec, the discrepancy isn't quite as wide as these numbers suggest.
The Moto Z measures 16 percent lighter than the HTC 10, but this too will change once you snap a mod onto the back of the Moto.
As we mentioned, the Moto Z has a modular focus with its snap-on back plates that add either a different look/feel, extra battery life or entirely new features (more on those in a minute).
Motorola says the Z is made of steel and aluminum, while the HTC 10 has one of the smoothest-looking aluminum unibody designs around.
Motorola will also have some "Style Shells" that put different materials on the back, like wood, leather or patterned fabric.
The Moto Z's main body only ships in four different color options (and all but the white model have black fronts), but once you put the modular back plates into play, its options get wider – and can continue to widen, indefinitely.
The Moto Z has a 12 percent bigger screen.
Both have ultra-sharp QHD resolution. The HTC 10's smaller screen, though, gives it a 6 percent higher pixel density.
It's AMOLED vs. IPS on the display panel front.
That asterisk next to the Moto's battery capacity is courtesy of its battery mods. The optional Incipio OffGrid mod snaps onto the phone's backside to add an extra 2,220 mAh to its total. It's like a battery case you'd buy for any other phone (and every bit as thick and heavy as one), only more integrated into the phone itself.
Like all modern Android flagships, both have quick-charging tech onboard.
The only way you'll get wireless charging on either phone is through one version of the Incipio OffGrid case for the Moto Z. There's a version that has wireless charging (and is more expensive), and another that doesn't.
Both handsets run Qualcomm's zippy Snapdragon 820 processor. It's the current benchmark for high-end 2016 Android phones.
We're also looking at a (currently standard) 4 GB of RAM either way.
You won't see the 64 GB HTC 10 in the US, but otherwise both phones offer the same internal storage options.
You also get expandable storage no matter which you choose.
We haven't yet put the Moto Z's camera to the test, but the HTC 10's is one of our two top picks in this category (alongside the Galaxy S7).
Camera aperture (rear)
Here's a promising sign: the Moto Z matches the HTC 10 in aperture, which could bode well for its low-lit photography (HTC's phone is already in excellent shape there).
Both phones' rear cameras have Optical Image Stabilization, while the HTC 10 goes one better with OIS in its front-facing camera.
The HTC 10 is outstanding for audio, and unless you count the hard-to-find B&O add-on for the LG G5, HTC's phone is our top pick for best smartphone audio, with its built-in amp and 24-bit DAC. Plug in (or pair) some quality headphones and you'll enjoy some unusually rich and smooth mobile sound.
Like pretty much every high-end phone you can buy today, each of these has a fingerprint sensor.
Sitting below its screen, you might expect the Moto Z's sensor to double as a home button, but we discovered during our hands-on that it instead doubles as a sleep/wake/power button.
We're venturing into Nicheville here, as one of the Moto Z's mods lets you share its screen as a 70-inch projection on the wall. Even if you don't have much use for that, this is the beauty of modular phones: OEMs can add features that cater to a select few, with no skin off of anyone else's back.
Another niche mod for the Moto Z, its JBL SoundBoost mod turns the phone into a little boom box (complete with kickstand) with some powerful sound. We'd prefer the HTC 10's better headphone audio (and the 10 has terrific built-in speakers as well), but if you want to replace your portable Bluetooth speaker (and sacrifice being able to do much with your phone while listening), this mod isn't a bad way to do it.
Like the HTC 10, the Moto Z will launch with Android Marshmallow, with updates to Android Nougat coming to both phones sometime down the road. Neither is completely stock Android, with each manufacturer throwing in some extra features, but the latest version of HTC Sense is fairly close to stock – and from what we could tell at Lenovo's launch event, the Moto Z is too.
Unfortunately the Moto Z launches as a limited-time Verizon exclusive, sometime this (Northern hemisphere) summer. It sounds like other US carriers and the rest of the world will have to wait until September.
Starting price (full retail)
The HTC 10's price varies a bit from carrier to carrier, but this is a roughly median price based on all of their prices (just note that the versions straight from HTC, including the unlocked version, are a pricier US$699).
At least we know what the HTC 10 costs; Motorola has yet to spill the beans on the Moto Z's pricing. Since there wouldn't be many compelling reasons to buy the phone without also buying a modular add-on or two, we're hoping Motorola keeps the phone's base price down to a respectable level – or, failing that, throws in a mod of your choice as a bonus. We'll see.
Want a cleaner, faster loading and ad free reading experience?
Try New Atlas Plus. Learn more