The one thing that no one seems to have mentioned yet is that in 1985 Lucasfilm struck a fresh interpositive of each film. For ANH, this is identical to the theatrical 1981 release. And except for the opening crawl/flyover, it is identical to the 1977 wide release and the international releases. Some previous English Language releases (primarily US, UK, and Japan) have 3 FX shots that are different. So if you compare the 1993/5/2006 version to previous releases you will see a difference in those three shots, but if you compare them to the Silver Screen Edition or 4k77 you will not. TESB and ROTJ are identical to all prior releases. The audio mix was updated, but according to sources here, only ANH had any edits and TESB and ROTJ are indistinguisable. The 2006 DVD releases of this version are unchanged except for in ANH the original 1977 crawl/flyover replaces the 1981 version. So they have the same picture and audio.