First of all, see Perry as usual for the complete published libretto of the stage-musical, as well as for stunning still photographs from the original London production!
Perry, George (1987). The Complete Phantom of the Opera . London: Pavilion Books Limited.
The reduction of the Gerik Phantom’s deformity down to “the glorified sunburn”.
See chapters/tracks 29-30 through 34 of the DVD.
See also the below links to Operafantomet’s Tumblr for some good photographic comparisons between the Gerik and a number of stage Phantoms.
Search Result: Deformity: Tumblr.com. http://operafantomet.tumblr.com/search/deformity
“have you done any photosets of varying Phantom's deformity?”: Tumblr.com. http://operafantomet.tumblr.com/post/106595238487/have-you-done-any-photosets-of-varying-phantoms
Search Results: 2004 Movie Deformity: Tumblr.com http://operafantomet.tumblr.com/search/2004+movie+deformity
Changes to the Phantom’s back-story in the Gerik.
See chapter/track 22 of the DVD vs Act II scene 2 of the stage-version libretto (see Perry). Compare Mme. Giry’s lines in both scenes, and also compare the history Mme. Giry recounts in Act II scene 2 of the stage-version vs the flashback in the Gerik.
Changes to the teacher/student relationship between the Phantom and Christine and its back-story in the Gerik.
See chapter/track 6 of the DVD vs Act I scene 2 of the stage-version libretto for where dialogue and visuals have been added in the Gerik, suggesting both that the Phantom has been Christine’s Angel of Music for much longer, and that she believes he may actually be the spirit of her father come back to teach and guide her.
See also chapter/track 9 of the DVD vs Act I scene 4 for comparison of the Title Song. Note that the stage-version contains four verses, whereas the Gerik version contains only the first three. Thus, the critical lines “In all your fantasies you always knew that man and mystery were both in you” are removed from the Gerik.
“Revealing the magicians secrets” - showing how the Phantom does his tricks and illusions, thus having the audience participate in unmasking him.
See chapter/track 3 of the DVD, where you see the Phantom’s hands untie the rope that causes the backdrop to fall onto Carlotta, compared to Act I scene 1 of the stage-version libretto, where you just see the backdrop fall and not how it was engineered.
See chapter/track 13 of the DVD, too, where you see what the Phantom is doing while his latest note is being read, vs Act I scene 8 and Act II scene 3 where you just hear his disembodied voice.
Similarly, see chapter/track 15 of the DVD vs Act I scene 9 of the stage-version libretto for a comparison of the two “Il Muto” scenes. Again, on the DVD you see what the Phantom is doing - how he makes Carlotta “croak”, etc. Whereas, in the stage-version, you only hear his voice.
Also, see chapters/tracks 16 and 28 into 29 of the DVD, in which you actually see the Phantom commit the murders of Joseph Buquet and Piangi, vs Act I scene 9 and Act II scene 7 of the stage-version libretto where you simply see the results.
Note, however, chapters 9, 11, and 25 of the Gerik DVD, in which it is implied that Christine is seeing things that are not actually there (the beautiful fairy-land of the catacombs and the light emerging from the mausoleum) without its being made clear whether this is simply her imagination or some sort of illusion or hypnosis by the Phantom.
Learn To Be Lonely.
See chapter/track 36 of the DVD, the end credits, for the only new song added to Phantom in the Gerik, entitled “Learn To Be Lonely”.