I recently bought a "well used" Snapon Solus Pro with Version 13.2 software on ebay for $400. Its the first SnapOn scanner I've owned so full disclosure I'm not qualified to exactly opine or provide experienced based recommendation(s) on the versions. But based on Schurkey's comment above my guess is that the 10.2 version was the 2nd release in 2010 which means it provides scanning, diagnostics, and bi-directional features for many domestic and import makes and models up to 2010. The 12.3 was the 3rd release in 2012 and so on....
In researching the Solus Pro subject before taking the purchase plunge I gleened that every passing year (version) includes newer vehicles AND additional interactive functions and feature sets. Furthermore backwards compatibility seems to be the general rule (for example the 10.2 version will support everything the 8.2 -10.1 versions supported), although, for some strange reason, occasional exceptions to this backwards compatibility exist (I've read claims that the programmers either forgot to include an earlier feature or decided to entirely abandon it due to pesty bugs or the law of unintended consequences). So you do need to exercise some caution and not blindly assume later versions ALWAYS support ALL earlier version function/feature sets. Here's a SnapOn support forum that covers some of these matters ---
https://askatech.autorepairdata.com/forum/showthread.php?t=13935
Thus far this scanner has already paid off in terms of my peace of mind in setting and verifying the CAM Retard is now within the +-2 degree spec (OCD sucks LOL). I'll be learning tons about the scanner's full capabilities in the weeks and months ahead. I'll post some of the more interesting learnings on a separate thread.