fumble vs mess up

fumble is a noun but mess up is not a noun.

Word	Noun	Adjective	Verb	Adverb
fumble	Yes	No	Yes	No
mess up	No	No	Yes	No

As verbs, fumble and mess up are synonyms defined as:

fumble (noun)	mess up (noun)
(sports) dropping the ball

fumble (verb)	mess up (verb)
drop or juggle or fail to play cleanly a grounder	make a mess of or create disorder in
feel about uncertainly or blindly	disturb the smoothness of
handle clumsily	make a mess of, destroy or ruin
make one's way clumsily or blindly
make a mess of, destroy or ruin