25th anniv edition was completely remastered so it comes with 2dvds, one is a 16:9 ratio version of the movie and one with a fullscreen version.
There are no extra dialogues/scenes in the 25th anniv edition tho IIRC. The DVD does contain a lot of extras though, making of transformers/commentary by the director/fan commentary/original tv spots and its remastered very well, so id watch the 25th anniv one any day.
you can search on youtube for the Remastering Side-by-Side Comparison of the two versions, although youtube is far away from judging quality, you will still be able to see the difference.