Two main differences ... If you get film tints you can have really really dark ones or ones which look like factory fit ones. Also on factory fit ones you can't see the rear window elements or have problems with the film adhering over the dot matrix around the rear window.
I hate seeing elements when you have film tints done :yuck: lol
But some manufacturers (FORD) give you the option of really dark privacy glass which isn't film tint and they look so good!