fluff vs comb out

fluff is a noun but comb out is not a noun.

Word	Noun	Adjective	Verb	Adverb
fluff	Yes	No	Yes	No
comb out	No	No	Yes	No

As verbs, comb out is a hypernym of fluff; that is, comb out is a word with a broader meaning than fluff:

fluff: ruffle (one's hair) by combing the ends towards the scalp, for a full effect
comb out: smoothen and neaten with or as with a comb

Other hypernyms of fluff include comb, disentangle.

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

fluff (verb)	comb out (verb)
ruffle (one's hair) by combing the ends towards the scalp, for a full effect	smoothen and neaten with or as with a comb
erect or fluff up	remove unwanted elements
make a mess of, destroy or ruin