fumble vs screw up

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

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

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

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

fumble (verb)	screw up (verb)
drop or juggle or fail to play cleanly a grounder	twist into a strained configuration
feel about uncertainly or blindly	make more intense
handle clumsily	screw or turn higher
make one's way clumsily or blindly	make a mess of, destroy or ruin
make a mess of, destroy or ruin