bungler vs fumbler

bungler and fumbler both are nouns.

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

As nouns, bungler and fumbler are synonyms defined as:

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

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