IMO if "fantasy" tries to explain things as being technology, it's (soft) sci-fi. If it describes it as magic, then it's fantasy.
replyTechnobabble is just tech-sounding magic.
replyThey 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.
replyPersonally 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.