To the best of my undetanding the pre production version is what fett looked like, once they made the suit. It was used for promotional shots etc. Usually what the figures are based off of, though, fett was never very acurate.
Now, with fett, I have read multiple things. One was that the suit was stolen. Another was that the helmet was stolen after the movie. Another is that things just change.
I do not know whats tru, I just know that the 'pre-production' pictures are pictures of the 'intended' 'boba fett' before production started on the movie but after the fett character was change from the white 'super stormtrooper' to the lone bounty hunter.