The premium had higher quality paper and print quality from what I remember, however I can't find a source right now.
Here's a source: Yes that's correct, it was called "premium" because I used the highest available print quality. If I recall the difference was quite small, but printing cost about double.
Interestingly I still have a handful of "scraps" of the signatures and holograms leftover from the Autographs Edition, I don't know how many but I'd say about 20 substantial sets, which could be used in some special way down the road.