The M9 is just the "Military" version. It has a few slight differences over the commercial 92FS, these are a slight difference in the grip, as well as a straight dust cover, and fancy military markings. The sights are also a two dot sight compared two the three dot sight of the 92FS. Go on youtube and search for 92FS vs M9. Their is a video by a guy called windmill or something. he goes over the differences.
As for the Ionix, I think its just a pimped out version, but I don't really like the silver look so I never really looked into it.