The other version of Legend would be the International cut that was distributed in 1985 by Fox outside of the United States. I used to have a pan-and-scan videocassette of that somewhere, years ago, primarily because I really wanted to see the film with the Jerry Goldsmith score. The Director's cut seems to be an expanded version of what I remember from the European cut. I could be wrong. If I can find that VHS tape I could be more specific, but I'm not optimistic about that.
The American version is the only one with the redone Tangerine Dream score, and was significantly re-edited when Universal exec Sidney Jay Scheinberg decided to target the Risky Business audience with the film (at the same time, he was trying to “improve” Terry Gilliam's Brazil — not his best year). Although Scott participated in creating the American cut, he did so reluctantly. Different footage is used throughout, Darkness' introduction is different, the kiss from the end of the movie was added to Tom Cruise and Mia Sara's first scene together, the alicorn is returned to the unicorn that was attacked by goblins at the end of the film.
The biggest difference between the cuts is the music. I actually like Tangerine Dream's score for the American cut, despite the accusations of it being anachronistic (I find that this is rarely a good argument — how is a modern symphony orchestra not anachronistic for the pre-historic Conan the Barbarian?) and too Eastern for the very Western-styled fairy tale. It's very moody, with some quite moving passages, and is pretty effective. Jon Anderson's vocals were added to the last cue of the film, apparently without the Dream's approval.
But Jerry Goldsmith's music, at times Romantic and at others impressionistic, is sublime. The film was planned with this approach in mind; the John Bettis lyrics for the songs were in the script. It is much more adept at creating the fairy tale atmosphere than the Dream, and there is one scene, where Jack begs the unicorn for forgiveness, where Goldsmith is effectively the “voice” of the unicorn, communicating its anger at Jack, fear and ambivalence, and ultimately absolution.
(There are a few cues from the composer's earlier Psycho II thrown in; it wouldn't be a Ridley Scott/Terry Rawlings project without a little jarring temp track love, would it?)