No huge difference here, but the HTC One (M8) is a little bigger. It's about 6 percent longer, 3 percent wider, and 9 percent thicker than the Nexus 5.
The One M8 isn't a ridiculously heavy phone, but it is noticeably heavier. It gives you 23 percent more heft than the Nexus 5.
I don't have a problem with the Nexus 5's matte plastic finish, but there's no doubt that the One M8 has the higher-end construction. Its aluminum unibody finish riffs off of the design we saw in last year's One (M7).
Right now we're looking at three color options for each phone. Though I wouldn't be shocked if we saw a few more One M8 colors roll out later this year, as we saw with the 2013 version of the One.
Both phones give you sharp and spacious screens. The differences here are pretty trivial, and probably not worth basing your decision on.
Both phones also use onscreen navigation keys. So outside of apps that use Android's Immersive Mode, those virtual buttons will always be camping out at the bottom of your screen, taking up a little real estate.
The One M8's Motion Launch is a set of sensor-based shortcuts. We're looking at things like tapping or sliding on your sleeping phone's screen to jump straight to your lock screen, home screen, or widgets. It's also things like launching your camera app by holding the phone in landscape mode and pressing a volume button, or answering a call by lifting the One to your ear. Simple, but also very convenient.
Internal storage options are even, though the HTC One does also have a micro SD slot on board this time around.
Battery capacities are pretty close, but in our hands-on battery test, the One M8 spanked the Nexus 5 pretty hard. Streaming video, with brightness set at 75 percent, the One lasted 107 percent longer than the Nexus 5. Battery tests can vary a bit based on wireless signals and other factors, but we think the One M8 is easily the longer-lasting phone.
Extreme Power Saving Mode
Like the Galaxy S5, the One M8 is going to have a cool new feature that lets you squeeze some serious juice out of your phone. If your battery life drops down to a critical level, jump into Extreme Power Saving Mode, and the screen will go black & white, with background apps and processes more constricted. The result? Hours of extra battery life out of just a very small amount of juice.
The only catch is that, unlike the Galaxy S5, the One M8 didn't launch with this feature. It will be coming soon via software update.
The Nexus 5 looks better on paper, but the One's larger pixels ("UltraPixels" as HTC likes to call them) make it one of the best options for capturing shots in low-lit conditions.
The One also has an unusually high-resolution front-facing camera. So if you're into selfies (any 16-year-old girls in the house?), the M8 might be just what the doctor ordered.
The One M8 has a second rear camera that's there just to sense depth. It can create some unique effects, including a blurred-background (bokeh) feature called UFocus. It's a little hit-or-miss, but when it's on the mark, it can make for some striking shots ... well, at least for a smartphone camera.
Slow-motion video recording
Like a lot of high-end phones from the last six months or so, the One M8 lets you shoot slow-mo videos.
Dual LED flash
The One's dual LED flash helps to make your flash photography look more even and colorful, and less washed out.
When you go shopping for a new phone, do you make speaker quality your highest priority? Yeah, me neither. But it is a nice bonus that the One M8's front-facing speakers pump out the best built-in smartphone audio I've heard.
Performance isn't an issue with either phone. The One M8 has the slightly-updated 2014 version of the Nexus 5's Snapdragon 800 processor living inside.
RAM is even, at 2 GB a pop.
Both phones run Android 4.4 KitKat. But they have completely different UIs, including some extra features thrown in on the One. That's all thanks to HTC's Sense UI, while the Nexus runs stock Android.
The One hit the market about five months after the Nexus 5 first went on sale.
Starting price (off-contract)
This is the Nexus 5's killer feature. You could easily argue that the One M8 is the better all-around phone – in fact, I'd probably vote for the new HTC One as the best smartphone you can buy today. But when you look at overall value, the Nexus 5 is really hard to beat. It isn't every day that you see a phone with high-end hardware and the latest version of Android ring up for US$350 off-contract.