I think "Film" is more British English and "Movie" more American. But I'm not a native speaker, so I could be wrong

In US English they can be synonyms and have sightly different tones. "Film," of course, literally refers to the transparent strip of material wound on the the reel, with little pictures on it. "Movie" is the most common everyday word, but "film" is common, too. "Movie" is a nickname for "moving picture" or "motion picture," and it is slightly informal. The organization that presents the Oscar awards is the "American Academy of Motion Picture Arts and Sciences," not the "American Academy of Movies." "Film" is neither formal nor informal. It would be natural to say to a friend "I saw a good film last weekend." But there is also dignified organization called the "American Film Institute," and "George Lucas, director of 'Star Wars,' went to film school at USC." There is a third word that is a step up in formality from "film:" "cinema." As a matter of fact, the USC film school doesn't called itself a "film school," it is the "USC School of Cinematic Arts."

Film can be used both to refer to a specific production [a film, the film] or the artistic activity in general. Movie, originally an American word but now used generally, means a particular film.

A film can be a cinematic video of any length. A movie is just a long film usually over an hour.

I think the other hinted at this but: MOVIE can refer to any sort of movie, film, etc. (sorry, that wasn't a very good definition). FILM is generally used for more 'artitistic' movies. e.g. most people wouldn't refer to a silly comedy with lots of flatulence jokes as a FILM. You might think of a movie as a commercial product and a film as a work of art. But it's often difficult to draw a line between the two.