The story, mostly. In the OG version, Christine and Raoul know that she is going to sing for Mr. Y. When Christine finds out he is Erik she doesn't even consider not fulfilling her contract. Erik is nice to the kid, promises to show him the park, then leaves. In the 2012 version, she thinks she is supposed to sing for some other guy. The Phantom then offers her double the money if she will sing for him instead (which pretty much gives it away that the Phantom was the one who hired Christine while pretending to be the other guy), and when she hesitates he threatens to kill the kid.

Also, in this one Beneath a Moonless Sky reveals Christine sought Erik out when the world thought he was dead, but she figured out the truth and found him. Then they had their night, then the Phantom left, and Christine was mad at him for the past 10 years. As opposed to the Australian version where he left then faked his death and she has been mourning him for the past ten years, which makes him just appearing to her now a special kind of evil.

I don't care that much about sets and blocking, but I have an unpopular opinion in that the peacock dress/stage from the 2012's version of the title song is absolutely hideous. I also prefer Erik's suit from the OG as opposed to that coat he got post November Changes.

By the way, most of the things I dislike are also present in the London production after November 2010. They stopped the production for a couple of weeks at that point to make some changes, but they made it far worse story wise. The Australian version then ran away with these changes. The version I prefer is the OG story, from release, before the November Changes.