bungler vs stumbler

bungler and stumbler both are nouns.

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

As nouns, bungler and stumbler are synonyms defined as:

bungler and stumbler: someone who makes mistakes because of incompetence

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

bungler (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