fluff vs blunder

fluff and blunder both are nouns.

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

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

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

fluff (noun)	blunder (noun)
a blunder (especially an actor's forgetting the lines)	an embarrassing mistake
something of little value or significance
any light downy material

fluff (verb)	blunder (verb)
ruffle (one's hair) by combing the ends towards the scalp, for a full effect	utter impulsively
erect or fluff up	make one's way clumsily or blindly
make a mess of, destroy or ruin	commit a faux pas or a fault or make a serious mistake