How many alternative versions of M. Bison exist? True, Final, II ...?

I checked some websites and there are references to different versions of M. Bison. In addition to its "normal" version, and the "Final Bison" Street Fighter Alpha 3, also read about "Bison II" Street Fighter EX 2 and "True Bison" Street Fighter EX 3. On these last two, which they differ? What differs from the "Final Bison" of SFA3?

http://streetfighter.wikia.com/wiki/True_Bison
http://streetfighter.wikia.com/wiki/M._Bison_II
http://streetfighterdevotion.com/characters_truebison.php