In the musical, the story occurs in 1881, the movie in 1870 (a historical fallacy, because that means France would've been in the middle of a war.)
In the movie the ages are all shifted closer to the book. On stage Christine and Raoul are in their 20's, Phantom in his late 40's-50's.
Mdm. Giry was never Christine's caretaker.
In "Think of Me", the backdrop falls, but it doesn't actually hit Carlotta, it just frightens her.
Almost all of the costumes are different. In the stage show, the Phantom himself always wears a white tie and tuxedo, but also wears a large black fedora, which is missing from the movie.
There's no horse in the underground scene (that was an additon from the book),
In the ballet scene of "Il Muto", the stage version has the Phantom's shadow behind the backdrop, scaring the dancers, the movie doesn't have this.
Many of the Phantom's actions in the stage show are not explained, giving him a more ghostly persona, however in the movie, most of his actions are shown/explained, to emphasise that he is simply a man, not a ghost, ie in the stage show, he 'magically' makes Carlotta sound like a frog, and laughs maniacly when Carlotta starts croaking, however in the movie, we are shown the Phantom swapping Carlotta's throat spray, in order to achieve this effect.
The chandelier drops after "All I Ask of You" at the end of Act 1 on stage, instead of at the end in the movie, this also prompts a lyric change in Masquerade from "to the new chandellier!" to "to our friends who are here!"
In Masquerade, the costumes are very bright and colorful in the stage versions, with people dressed as animals, clowns, and other creatures, wheras in the musical, the costumes are simplified, but more ballgowns than costumes. Andre and Firmin dress in skeletal costumes on stage, but in the movie dress in different costumes.
Also, a reprise of "Notes/Prima Donna" that takes place after "Masquerade" was edited down, and then rearranged throughout the movie, as were many other "Notes" scenes.
The Red Death costume on stage has a full skull mask, with moving jaw, and a big red fedora with a plume, this costume is also much more ornate than the movie version.
The mirrored room wasn't in the stage version, but another addition originally in the book.
The original reprise of "Notes" was combined with "Why so silent?"
A rehearsal scene of "Don Juan Triumphant", in which the cast go through their first play-through of the show, but dont take it seriously, and Piangi cant sing properly, until the Phantom posesses the piano, and everyone suddenly sings perfectly, was completely taken out.
In the stage version, of the cemetery confrontation, the Phantom conjures up lightning and shoots fireballs from his staff, instead of sword fighting with Raoul.
In "Don Juan Triumphant," the Phantom does not wear a stylised Latin outfit, but instead wears a cloak completely over his body and head.
There are no tango dancers in "Don Juan" / "The Point of No Return" in the stage version as the scene is set in a banquet hall with the cast wearing traditional costumes and sat around eating, wheras the movie version is set in a set which looks like Hades, and has a Latin feel.
The Phantom is far more deformed in the stage version than the movie. In the movie he has bumpy, discolored skin and thinning hair, wheras in the stage version he has giant cracks in his skull, whispy hair, one of his eyes is whited out, giant swollen lips, burns, cuts and generally more deformation.
When unmasked in "The Point of No Return", he runs off out of sight with Christine instead of dropping through a trap door.
Instead of smashing a mirror and leaving through a secret passage after Christine and Raoul leave, the Phantom sits in his throne, and covers himself with his cape. Meg is the first to arrive in the lair, and lifts the cape from thr throne, to reveal that the Phantom has disappeared, leaving only the mask.