Supposedly, the only major change in later drafts is that Leia dies earlier and that
Snoke but WorseTor Valum is replaced by a holocron, though obviously that’s hard to confirm without the scripts.
Another major change is that the fight at the end is a 3-way fight between Kylo, Rey, and this Knight of Ren girl called Sollony, who’s the new Phasma, basically, and is there at the end so Kylo isn’t the final enemy.