blunder vs fluff

blunder and fluff both are nouns.

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

As nouns, fluff is a hyponym of blunder; that is, fluff is a word with a more specific, narrower meaning than blunder:

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

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