I was talking about different kinds of stories to my students and the term "fantastic" emerged. I guess the most appropriate phrase is "fantasy story" but can you also say "fantastic story" ?(to talk about the fantastic genre)
There is a genre called 'fantasy', but not one called 'fantastic'.
Any book/film may be described as fantastic (or not),
and a book/film may contain elements of the fantastic without being considered part of the fantasy genre;
eg. Hamlet and Macbeth are tragedies with fantasy/fantastic characters like ghosts and witches.