flub vs fluff

flub and fluff both are nouns.

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

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

As verbs, flub and fluff are synonyms defined as:

flub (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

flub (verb)	fluff (verb)
make a mess of, destroy or ruin	ruffle (one's hair) by combing the ends towards the scalp, for a full effect
	erect or fluff up
	make a mess of, destroy or ruin