We already know that the new HTC One (M8) isn't exactly a radical departure from last year's HTC One (M7). But are there enough new goodies there to justify the upgrade? Let's compare the features and specs of the two flagships, and see if we can point you in the right direction.

Size

The HTC One M8 is about seven percent longer and four percent wider than the 2013 One. It's also a negligible one percent thicker.

Weight

The new M8 is almost 12 percent heavier than its predecessor. When you take its longer frame into account, though, I don't think the extra weight is anything to worry about.

Build

Still aluminum, though the new model has a smoother, more rounded feel in hand. There's also a fine brushed finish on the surface of the gun metal version. You could easily argue that the original One was the sharpest-looking phone ever made, and the new model only builds on that.

Colors

These are all the color options you'll find right now for each phone. Just know that some of the original One's colors are carrier or retailer exclusives, and won't be available everywhere.

Display

The One M8 gives you 13 percent more screen real estate than the original did. But it also has onscreen navigation keys, whereas the 2013 One had capacitive keys sitting below its screen. So in most apps, the usable area won't be much different.

The big exceptions, though, are apps that use Android's Immersive Mode. When you're doing things like watching videos, looking at photos, or reading Google Play Books, the navigation buttons will disappear.

Both phones have 1080p resolution. Though that means the One M8 has a slightly lower pixel density, I can vouch that it still looks extremely sharp. I'd be shocked if you noticed any difference from the One M7's stellar display.

Storage

HTC cut down on the internal storage options this year, but added a micro SD card slot. Unless you live in China, you won't find one of those in the OG One.

Motion Launch

One of my favorite features on the One M8 is called Motion Launch. It lets you jump straight from a sleeping phone to various areas of the phone's software, just by tapping or sliding on its sleeping screen. It also lets you answer a call just by lifting the phone to your ear.

Though the original One will be updated to Sense 6, an HTC rep tells me that Motion Launch relies on sensors that the M7 doesn't have. So if you own the OG One, no Motion Launch for you.

Front-facing speakers

The original One's front-facing BoomSound speakers were the best I'd heard from any smartphone. That changed after I used the new One M8. They sound noticeably richer, crisper, and fuller.

Cameras

Here's something we've never seen before: a phone that has more megapixels in its front-facing camera than in its main rear shooter. That's because both Ones have larger pixels in their rear cameras (HTC calls them "UltraPixels"). Among other things, they help to make both Ones great at snapping pics in low-lit conditions.

The One M8 also has a second rear camera. Its sole purpose in life is to sense depth. That opens the door to our next category ...

Depth of field effect

The One M8 has a feature called UFocus, that lets you simulate the narrow depth of field ("bokeh" effect) that you'd get from a much better camera with a wide-aperture lens. Just snap a regular pic, then go back and edit it to add the UFocus effect. You can even save different versions of the same shot, each with a different point of focus. In my tests so far, it's a little inconsistent, but can look pretty damn good when you get it just right.

Zoes

Both phones have HTC's camera feature called Zoes. They're little three-second clips (made up of about 20 still frames) that the phone captures every time you snap a pic. You can pick from individual frames to find just the right shot, and you can also see the little mini-vids in HTC's gallery app.

Unfortunately, though, these last two categories are mutually exclusive. If you set the One M8's camera to Zoe mode, you don't get the depth-of-field features – and vice versa.

Slow-motion video

Both phones let you record slow-motion video. You can edit which parts of the video play slowly, and which play full-speed, after the fact.

Battery

The new One's battery holds more juice, and HTC promises up to 40 percent longer battery life. From my tests so far, it does look like it's draining pretty slowly.

Processor

I never thought there were any performance concerns with the One M7's Snapdragon 600, but the One M8's Snapdragon 801 is newer and faster.

RAM

We're still looking at 2 GB of RAM in the new model.

Software

The One M7 has technically been updated to KitKat, but not every carrier has pushed out that update. So if you bought the 2013 model now, it's possible you'd still be on Jelly Bean for a little while.

Of course on both phones you have HTC's Sense UI sitting on top. I think it's one of the subtler and more sophisticated custom Android skins. The original One is still running Sense 5, but HTC says it will soon get updated to Sense 6.

Dot View case

One of the quirkier aspects of the One M8 is its Dot View case. If you want to quickly glance at, say, the time or notifications, then you can see Lite-Brite-esque versions of them through the case's mesh flap. The case is going to retail for around US$50.

Release

Hey, what do you know? Like most smartphone makers, HTC released its new flagship at about the same time that its predecessor shipped the year before.

Pricing (off-contract)

The One M7 looks like it's still going for about $600 off-contract, but you might want to keep your eyes out for some sales or bigger price drops. The new M8 is starting at $200 on-contract on the big US carriers.

For more on the One M8, you can hit up our announcement post, our hands-on from HTC's launch event, and our early impressions of our review unit.