Is 'through the looking glass and what Alice found there' different from 'through the looking glass'?

The story as told in the book of Lewis Carroll is more extensive and detailed if you compare how the story is told in the film "Alice Through the Looking Glass" (sic). Furthermore, the original title of the book is: "Through the Looking Glass and What Alice Found There", as this is a long title is common abbreviate it so: "Through the Looking Glass", the film has a title that begins with the word "Alice". There are characters and scenes in the movie that are not on the book by Lewis Carroll and vice versa.