Restoration almost always means going back to the original elements (where possible) and repairing damage, not just making a new transfer to serve as the basis for a new release. For example, I wouldn't call a BD release a restoration just because it uses a new scan from the original negative: there would have to be more to to it than that. For this reason, I am wary of the term "fan restoration". To me, studios are involved in restorations, and it's highly improbable (but not impossible) that fans would be; therefore, I would combine categories 2 and 3, between which (as defined above) I don't see any meaningful difference. (I strongly agree with most of what Catbus wrote in the first few paragraphs of post #3.)