Update: We've published our hands-on look at these two phones.
These days, the iPhone is by far the smallest high-profile flagship phone around. The Galaxy S5 is 15 percent longer, 24 percent wider, and seven percent thicker than the 5s.
Smaller phones tend to be lighter, and the iPhone is no exception. It's 23 percent lighter than the GS5.
The iPhone 5s is made of aluminum, and not pretending to be anything but. The GS5, meanwhile, has a faux leather finish – complete with dimples. An interesting choice by Samsung, to say the least.
These are your four color options for the GS5, and three hues for the iPhone. Just know that your carrier might not sell all four versions of the GS5.
The Galaxy S5 has a much bigger and sharper screen. It gives you 62 percent more real estate and 185 percent more pixels than the iPhone. We don't want to get too carried away with pixel counts, as the iPhone's Retina Display, while much lower-res, still looks pretty damn sharp. But its 4-in size is another matter: it's looking very small next to just about every other high-end phone out there.
Samsung is aiming straight at the iPhone 5s' killer feature, the Touch ID fingerprint sensor, with a fingerprint scanner of its own. One big difference is that, on the iPhone, you can unlock your phone by simply resting your finger on the home button for a moment (usually less than a second). On the GS5 you have to swipe your finger from the bottom of the screen down to the home button.
One thing the GS5's scanner has going for it is a Samsung partnership with PayPal. You can use your print to authorize payments associated with the popular service. The iPhone's fingerprint payment options are limited, for the time being, to the iTunes and App Stores.
Heart rate monitor
Samsung is throwing more chips into its S Health pot this year. Not only is it launching its first dedicated fitness tracker, the Gear Fit, but the GS5 has its own heart rate monitor on board. The sensor lives just below the phone's rear camera.
If you live in a region that has LTE, then you'll likely get a GS5 that has Qualcomm's new Snapdragon 801 inside. Other areas will, as with previous Galaxy flagships, find some Exynos octa-core silicon inside.
The GS5 doubles the iPhone's 1 GB of RAM.
The iPhone has an extra storage tier on the high end, but the Galaxy S5 supports microSD cards – including SanDisk's new 128 GB card.
Samsung's phone holds quite a bit more juice, but it's also powering a display with many more pixels. Consider this one an incomplete until we put the GS5 through some extended testing.
Ultra Power Saving Mode
One of the most eyebrow-raising new features in the GS5 is called Ultra Power Saving Mode. You can set the phone so that, if it reaches a critical level, it shifts to a black & white display and severely limits background processes. Samsung says that UPS mode can squeeze an extra 24 hours of uptime out of a mere 10 percent charge. If that claim is legit, this could be a big-time innovation.
The GS5's camera easily wins on megapixel count, though its camera-based features might have more of an effect on your shots ...
That includes Samsung's Selective Focus feature, which lets you choose what part of a shot to focus after you've already snapped the shutter.
4K video recording
Samsung also gave the GS5 4K video recording capabilities. That might not be a huge selling point right now, considering how few of us own any screens capable of displaying 4K content. But at least you'll know that your phone is future-proofed, in case you do eventually throw down for an Ultra HD TV.
Like the iPhone 5s, the Galaxy S5 also has the ability to record video in slow motion, at 120 frames per second.
If you fancy turning your phone into a TV remote control, then the GS5 delivers.
Like last year's Galaxy S4 Active (as well as most recent Sony Xperia flagships) the Galaxy S5 is water and dust resistant, with a rating of IP67.
The GS5 launches with Android 4.4 KitKat, and a thick layer of TouchWiz smeared on top. This time around, though, the company appears to have resisted the urge to add a bajillion new features to the custom skin.
The GS5 drops on April 11, though some regions and carriers are sure to see the flagship rolling out a little later. The iPhone 5s has been around since September, meaning we're probably about halfway towards its sequel ... that is, if Apple sticks with the same release slot this year.
Starting price (off-contract)
No word yet on pricing for the GS5, though the same launch prices as the Galaxy S4 are probably a pretty safe bet.