The changes were relatively minor, especially between ESB and ROTJ. The most obvious difference is between ANH and the rest;the robe lies over the armor, the mask and helmet are larger, with a more pronounced 'widow's peak',and the chest box details are different. The ROTS suit is also unique in that the mask is symmetrical and has a longer neck that rides inside the collar of the armor(this is what allows him to fold his arms, at the expense of most head movement). This version has different shoulder bells than the others, and (yet again) it's own details on the chest box.Each has it's own advantages and disadvantages for the wearer; my suit is sort of a composite Empire-Jedi version, though I have a 'New Hope' mask. A friend of mine has the 'Sith" suit, and rather envies my head mobility...PS
I'll post pix when I take some new ones...