"Creep me out": almost always used when something either scares you or disgusts you. *That guy is staring at me. It is really creeping me out! ... *I saw a spider today. They creep me out. "Freak me out.": almost always used in cases of fear, especially shocking/sudden fear.. rarely used to mean disgust. *That cat jumped out from behind the tree! It freaked me out! *Did you see that lightning?! Wow, that freaked me out! Hope this helps! ^^

Interchangeable? :) Well, "freak" means more of a shock value. Something totally unusual. But "creep" is more an uneasy feeling... like insects creeping all over you. Neither is vulgar, but for informality I vote for "freak" (winning by a nose). Maybe because informal speech may tend towards more dramatic phrases?

Phrase "Freak me out" is more uses. I heard it from a lot of movies, but "creep me out" I didn't hear at all

i'll vote for "Freak me out", but not 100% sure.