As with any genre, nothing is distinct or easy to categorise and no-one agrees on the definitions!
There are such huge overlaps - a slasher film is as much "crime" as "horror", a supernatural horror film is also fantasy, SF is often horror and vice versa etc etc.
Things like
Topper are comedy first and foremost, they just happen to have a ghost in!
"Fantasy" is far to broad a concept to be a useful term anymore I think. Most people just think of Tolkeinesque stuff when faced with the word, sadly.