Several scenes cut from the theatrical release have been reinstated. I have never seen the original, but hope to make a direct comparison at a later date. According to IMDB, in the Director's Cut, the Judge has more dialogue, and scenes in Frank's house between Cyrus and Stuart have been returned. Extra scenes while Frank is in jail with Stuart and Cyrus and Dammers are also included. Dammers has extra dialogue as he reveals his mutilated chest.
The shot of Dammer's head exploding, sometimes cut for TV, is intact.