There are no changes to the films themselves. What you get is a feature-length on-set documentary about each installment on the second disk, and then the first disk is a double-sided one which contains both the theatrical cut and the extended cut of each film--the films are split with an intermission the same way the original extended editions were, with part 1 on side A and part 2 on side B, and the two versions are both it fit on the single disk via seamless branching. Bitrate wise, they are identical, and FOTR theatrical cut is even a better than the original 2001 version since compression technology is so much better now.