A good definition of a "fantasy" movie is a movie where the plot deals with fantastical elements but does not include, as a principal plot driver, future technology. Future technology may be defined as anything post dating today's current public technology level.

A good definition of a "scifi" movie would be a movie where future tech is central either to the plot or as devices used by the characters.

A good example of "scifi" is Star Wars

A good example of "fantasy" is Lord of the Rings

The closest merger of the two genres I can think of, but would still classify as a "fantasy-adventure", is Krull (the one with the star blade weapon that you can throw)