They have different writing styles generally, but it is still pointless to call Star Trek a fantasy for the same reason why you wouldn't call Lord of the Rings a science fiction. If you have a spectrum from fantasy to science fiction with 5 being the middle then maybe Star Trek would be a 6 and Star Wars being more of a 5.
Personally I'd classify Dune to be more of a fantasy than Star Trek just because of the style it is written in being very mystical and prophetic.
They have different writing styles generally, but it is still pointless to call Star Trek a fantasy for the same reason why you wouldn't call Lord of the Rings a science fiction. If you have a spectrum from fantasy to science fiction with 5 being the middle then maybe Star Trek would be a 6 and Star Wars being more of a 5.
Personally I'd classify Dune to be more of a fantasy than Star Trek just because of the style it is written in being very mystical and prophetic.