boo-boo vs fluff

boo-boo and fluff both are nouns.

Word	Noun	Adjective	Verb	Adverb
boo-boo	Yes	No	No	No
fluff	Yes	No	Yes	No

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

boo-boo (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

boo-boo (verb)	fluff (verb)
	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