This is one of those extremely confusing Sony isms, so rather than explain every spec in excruciatingly painful mumbo jumbo, I will keep it straight and simple.
The S2 is great for videographers looking for a small format camera, with a full frame sensor, that can do amazing things. The S2 is incredible in low light with useable ISO up to 102,400, has 5-axis sensor stabilization, Sony's s-log processing, and can shoot up to 120fps in HD 1080p at 100mbps. The camera also shoots 4k video up to 30fps. Still photos look great and are captured at 12.2 Megapixels.
The R2 is a still photography beast at 42.4 megapixels. It also boasts more than double the amount of autofocus tracking points than the S2. It still shoots 4k video, but the lack of s-log3 means that it lacks the low light detail. 120fps video is also limited to 720p recording.
In a nutshell, buy the S2 if you're looking for the best video performance with very good stills, or buy the R2 if you're looking for amazing stills and video as a secondary consideration.
Both cameras offer NFC and the ability to transfer photos to your iPhone or Android device using the Sony Playmemories app. Neither camera has built in GPS.
For travel, this camera is small enough to fit in a jacket pocket when equipped with a 28mm f2.8 Zeiss lens, but something like an Olympus OMD is still smaller if size is the biggest concern. From a price standpoint, both of these cameras are very expensive and are likely going to be a b-camera for professional shooters, or an a-camera for travel photography enthusiasts.
Gear referenced in this post:
Chris Stenberg is a photographer, filmmaker, occasional wordsmith, and traveller. In his spare time you can find him hanging out with his family and/or biking and boarding in the mountains of British Columbia.