fluff vs foul-up

fluff and foul-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluff	Yes	No	Yes	No
foul-up	Yes	No	No	No

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

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

fluff (noun)	foul-up (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)	foul-up (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