fumbler vs blunderer

fumbler and blunderer both are nouns.

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

As nouns, fumbler and blunderer are synonyms defined as:

fumbler and blunderer: someone who makes mistakes because of incompetence

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

fumbler (noun)	blunderer (noun)
someone who makes mistakes because of incompetence	someone who makes mistakes because of incompetence