It's a small shade of difference, but it's a real difference. First of all, the actual stuff movies are made from, the actual medium of production, is film (a strip of film, 7,000ft. of film, and so on). When we discuss cinema, the division between film and movies is like the division between literature and fiction. In the same way that "50 Shades of Gray" is not literature to some people, "Scary Movie" is not a film to many. The catch here is that, with film, this difference is nearly moot; there are other words for describing movies: flick and motion picture among them, but look at the reviews on Rotten Tomatoes to see these all used in action. "Best film of the year." "Worst movie ever written." "I never thought a film like this could be made. Such genius." All films are movies, but not all movies are films.

You can use the word film or movie to refer to movies. Film may also mean a thin layer of something, for example, the thin coating that some people have on their glasses to help stop them from being scratched could be called a film.