I agree, the difference is basically nothing and both sentences make sense.
If you want to be reeeaaally specific, the two options have very subtle shades of meaning which are slightly different:
“Turn out to be” has an implication that the result was different to what you expected. Eg “the previews make the movies sound great, but they always turn out to be worse than you expect. I should remember that next time”
“end up being” is slightly more defeatist..you can imagine the speaker shrugging their shoulders a bit, probably in a bit of a bad mood and never really expecting it to be great. For example “every time I see a preview I know the film is gonna end up being worse than expected”.
I’m being so specific here - not at all important, but hopefully interesting!
Finally I would just say that even though both sentences are great and could easily have been said by a native speaker, the use of the word ‘worse’ is quite negative and implies that the movie is a bad movie. If you just wanted to say the preview gave you false expectations but the film was still quite good, it would probably be better to say:
“Movies are never as good as they seem in the previews.”