What is the difference between a movie novelization and a movie tie-in?

Movie tie-ins are more common than movie novelizations. They are editions of existing books published before a movie is released which feature actors or imagery from the film on the cover. These books are not adaptations of screenplays, but are original novels that have been re-issued to “tie in” to promote the release of a film based on the same book. Some well known examples include the movie tie-in editions of Harry Potter books, Lord of the Rings, and Superman: Last Son of Krypton.

A movie novelization, on the other hand, is a novel based on or adapted from a movie or screenplay, of which there are several different types. These can be faithful adaptations, or contain wildly different written material compared to what’s in the film.