Well, typically in such a piece, there might be elements like grand melodies. It could have rich harmonies often associated with the festive mood of Christmas. There may also be use of traditional Christmas musical motifs like bells or sleigh - bells sounds in the orchestration.
Yes. There is the original written version by Charles Dickens which has a very specific language and narrative style. Then there are film adaptations which often have to make changes for the visual medium. Some might cut certain parts, add new scenes for drama, or change the pacing, making them different versions in their own right.