I would have to go back and look at the 97SE, but there are clear differences between the '86 Japanese Special Collection LD and the '93 THX LDs - both of which are obviously different from the 2004 DVDs as well.

The most obvious changes are in the beginning of the film. The canyon scene with R2 and the Jawas was altered in '93 to make it appear later at night. Also, the wide shots of Luke and 3PO outside the homestead were altered to better match the closeups.

http://img407.imageshack.us/img407/8190/8693colorcompareee4.th.jpg

http://img407.imageshack.us/my.php?image=8693colorcompareee4.jpg