Samsung Galaxy S3 - Andriod 4.0 ICS with TouchWiz
Sony Xperia S - Android 2.3 (4.0 ICS update incoming) with Timescape UI
These phones will both run Android 4.0 Ice Cream Sandwich one day, but at present the Xperia still runs its grandpappy, Android 2.3 Gingerbread. Each phone has a custom user interface plastered over the top of Android. The Samsung Galaxy S3 has TouchWiz, and the Xperia S the Timescape UI.
For most people, the benefits come down to how these interfaces look and feel. In keeping with the serious, stylish look of the Xperia S, Timescape is a relatively severe, angular-looking thing. Its widgets tend to have sharp edges, and translucent grey panels abound rather than bright colours. There are some 3D animations going on here too, although thankfully they don't slow the phone like the did on Sony Ericsson's early Androids. It also packs-in Sony-specific software like Music Unlimited and Video Unlimited.
A quick glimpse at the Xperia S UI in action
The Samsung Galaxy S3's TouchWiz is altogether less serious-looking. Bright and more-colourful, it clearly cares much less about looking cool than the Sony alternative. Similar widgets are included, though, covering basics like clocks, social networking and calendars. Samsung also includes its own software suite. Top picks include the Siri-like S Voice app, which you can talk to when you get lonely - or ask to book appointments and open emails - and S Beam, which transfers files between devices using both NFC and Wi-Fi.
Samsung Galaxy S3 - MHL microUSB, 3.5mm headphone, microSD, Wi-Fi Direct, Bluetooth 4.0, NFC
Sony Xperia S - microUSB, HDMI, 3.5mm headphone, microSD, Wi-Fi Direct, Bluetooth 4.0, NFC
Predictably, the Samsung Galaxy S3 and Sony Xperia S cover all bases on connectivity, but their approaches are ever-so-slightly different. The Samsung does not offer a dedicated video output, instead using an MHL-enabled microUSB port. This is a relatively recent innovation in phones, and lets the port output HD video and surround audio.
A dying breed - on-body HDMI
Opting for the more traditional route, the Sony Xperia S has its own HDMI port, which can also output video and audio to a TV. Of course, in palm-to-face fashion neither phone comes with the cable you need to hook up the phone to the TV, which is an annoyance. Head over to eBay or a bargain electrical retailer, though, and you can pick one up for a few quid.
Other basics that feature in both include Wi-Fi Direct, which lets you transfer files between compatible devices without needing a broadband connection, and NFC. The Samsung Galaxy S3 makes particularly good use of NFC, with its S Beam feature, designed to make transferring files using it and Wi-Fi dead easy.
Samsung Galaxy S3 - 8MP, LED flash, 2MP user-facing
Sony Xperia S - 12MP, LED flash, 1.3MP user-facing
In pure spec terms, the Xperia S is the clear photographic winner. With 12 megapixels to its name instead of eight, they should be in different leagues. At review, though, we were disappointed with the Xperia S camera. Low light performance isn't great and the pictures didn't "pop" as much as those of the iPhone 4S. It does offer some extra modes such as Panorama, though.
We're yet to fully test the Samsung Galaxy S3 camera, but early impressions are good. It's very quick, and offers advanced features such as Best Shot, Burst Mode and HDR. Samsung has a history of producing great smartphone cameras in its high-end phones, and with any luck the Galaxy S3 could jump to the top of the phone camera rankings.
Samsung Galaxy S3 - 2100mAh
Sony Xperia S - 1750mAh
The Sony Xperia S has battery of lower capacity than the Samsung Galaxy S3, but thanks to a 0.5in smaller screen, it'll equate to roughly similar battery life. We're looking at a day and a half's solid use out of each - not bad for an Android device.
However, we'll be giving the Samsung a much more thorough road test in the coming weeks. You won't get a full week out of it, but with a 2100mAh battery in tow, there's a chance it'll noticeably outperform the Sony. Keep your eyes on TrustedReviews for the Galaxy S3 review.