They mean pretty much the same, but direct translation for each sentence is a bit different :). 나는 피가 무섭다(Adjective) = As for me, blood is scary 나는 피를 무서워하다 (Transitive Verb) = I find blood scary. Some Korean words can be confusing in terms of how they look like adjectives but are actually verbs and vice versa :)! e.g) 좋다 = to be good 좋아하다 = to like Hope that helps :)!

~이/가 무섭다 be scary ~을/를 무서워하다 to be scared of https://docs.google.com/document/d/1aEXzcDtEcrhRigmC6b7G__8NhhCjT1BtJR48zCTzHIY/edit

i think 무서워'한'다 is better 나는 ~이(가) 무섭다 나는 ~을(를) 무서워한다 i think these are almost same.