Both the Samsung Galaxy S4 and the HTC One run Android Jelly Bean, but there are considerable differences. For one, the Samsung smartphone launches with 4.2.2 and the One has 4.1.2. The custom skins used are quite different too.
Samsung's skin, TouchWiz, tries to stay relatively close to Android (the latest version more than ever), but piles on an impressive list of exclusive features that the Korean company developed for its flagship devices.
HTC's skin, Sense, goes for its own look and a number of exclusive features. The amount of home-backed apps is smaller compared to TouchWiz, but the experience is farther from stock Android compared to the Galaxy S4. It even goes as far as to offer two-button navigation.
The Samsung Galaxy S4 gets certain benefits from running the latest version of Android, specifically the lockscreen widgets and the notification area toggles. Of course, Samsung has tweaked both.
On the lockscreen, the right side pane, which normally launches the camera, is set to Favorite Apps by default (you can switch it back to being a camera launcher). Also, the images on the screen are randomly selected photos of beautiful travel locations pulled straight from TripAdvisor.
The notification area shows a row of toggles, a brightness slider and, of course, the actual notifications. There's a whole grid of toggles, and the top row is always visible. The full grid is revealed either by tapping on a button or by a two-finger swipe (similar to stock Android), but you can also just swipe the row horizontally.
The brightness slider can be hidden to save space and it has an Auto toggle. In Auto mode, it lets you tweak the automatic brightness algorithm, making the display brighter or dimmer than its ambient light sensor will suggest.
The homescreen on TouchWiz is pretty standard with only the Overview mode standing out as an addition to stock Android. We do like the small thumbnails that guide you when adding a new widget, they show the widget silhouettes, making it easier to find an open spot.
HTC One on the other hand sticks to the familiar Sense lockscreen with four shortcuts and time and weather info. There're a couple of different lockscreens available - Productivity (shows messages and calendar events), Photo album, Music and off.
The notification area has been stripped of the additions seen in previous Sense UI versions.
The homescreen is quite different though - the leftmost pane is entirely occupied by BlinkFeed, an event stream that combines updates from your social networking accounts with news sources to bring you relevant information.
The rest of the homescreen panes are the usual deal. You can set any of them as the default pane if you don't like BlinkFeed.
HTC has got rid of the Menu button and uses only two - Back and Home. But they don't quite work as you would expect, to get to the app switcher you double tap the Home key, a long press launches Google Now. The app switcher has been changed too, it shows a 3 x 3 grid of apps that you can dismiss by swiping up.
The Menu key is no longer part of Android, most apps use an on-screen button. Sense has an alternative, a swipe down that reveals a row of options. It's non-standard and third-party apps that require a Menu button will show a row at the bottom with an on-screen Menu button.
We won't argue which interface is better - it's a matter of personal preference, launchers and lockscreens are easy to change in Android. But the Galaxy S4 has a number of exclusive TouchWiz features over stock Android and the HTC One.
The biggest one is obviously Multi-window - it allows for two supported apps to run simultaneously, sharing the screen. How the apps split the screen can be adjusted as desired. Not all apps support it, though.
Another thing is Air View - the Galaxy S4 can detect your finger hovering over the screen and works similarly to the S Pen on the Galaxy Note II. It can preview info like the full text of messages and calendar appointments, give you a peek inside folders with images and preview what's ahead in the timeline of a video.
Then there are Air Gestures. A dedicated IR sensor above the screen can detect the direction of your hand waving over the device from several inches and serve to scroll web pages, change tracks and answer calls.
Smart Screen options are interesting too, they make sure the screen is rotated correctly (the accelerometer-based rotate gets it wrong if you're lying on your side), that the screen doesn't turn off while you're watching (or reading) and that the video will pause automatically when you look away and resume when you get back.
S Voice is also on board and while some of the functionality partially doubles that of Google's Voice Search, it can do more. It has a nice Car mode too, which simplifies the UI and makes the font bigger.
Winner: Samsung Galaxy S4. The Samsung smartphone comes with a newer version of Android that, while skinned, feels closer to stock Android. It has more flexibility too with many interesting features.
HTC Sense 5.0 is the best looking Sense yet, but HTC's experiments (BlinkFeed, only two buttons, etc.) will rub some people the wrong way. The lack of connectivity toggles is a bit too hard to forgive in 2013, too.