fumble vs blunder

fumble and blunder both are nouns.

Word	Noun	Adjective	Verb	Adverb
fumble	Yes	No	Yes	No
blunder	Yes	No	Yes	No

As nouns, blunder is a hypernym of fumble; that is, blunder is a word with a broader meaning than fumble:

Other hypernyms of fumble include bloomer, blooper, boner, boo-boo, botch, bungle, flub, foul-up, fuckup, pratfall.

As verbs, fumble and blunder are synonyms defined as:

fumble (noun)	blunder (noun)
(sports) dropping the ball	an embarrassing mistake

fumble (verb)	blunder (verb)
drop or juggle or fail to play cleanly a grounder	utter impulsively
feel about uncertainly or blindly	make one's way clumsily or blindly
handle clumsily	commit a faux pas or a fault or make a serious mistake
make one's way clumsily or blindly
make a mess of, destroy or ruin