I have 3 of the standard UV5Rs and two have upgraded antennas. I also had a mag mount antenna I used on the jeep with excellent results. Most of the trailing letters are simply aesthetics. My understanding is that the basic internals and software are pretty much the same, with minor tweaks. Most of the changes will be appearance only.
And since this thread has popped back to the top, I'll take a quick moment to mention the mounts I make for these radios.
http://www.expeditionportal.com/forum/threads/121298-Baofeng-UV5R-quot-Builder-Brackets-quot
Since the other forum isn't as well traveled as this I thought I would ask this here too (besides someone might be interested in the sale).
Does anyone know if the UV-5R V2+ with an extended battery works in this bracket? The extended battery version is on sale at Woot today ($35/unit + shipping) but I don't want to get it until I know it will work with a good mounting solution.