fumbler vs stumbler

fumbler and stumbler both are nouns.

Word	Noun	Adjective	Verb	Adverb
fumbler	Yes	No	No	No
stumbler	Yes	No	No	No

As nouns, fumbler and stumbler are synonyms defined as:

fumbler and stumbler: someone who makes mistakes because of incompetence

Other synonyms of fumbler include blunderer, botcher, bumbler, bungler, butcher, fuckup, sad sack.

fumbler (noun)	stumbler (noun)
someone who makes mistakes because of incompetence	a walker or runner who trips and almost falls
	someone who makes mistakes because of incompetence