top out vs crest

top out is not a noun while crest is a noun.

Word	Noun	Adjective	Verb	Adverb
top out	No	No	Yes	No
crest	Yes	No	Yes	No

As verbs, crest is a hyponym of top out; that is, crest is a word with a more specific, narrower meaning than top out:

top out (noun)	crest (noun)
	a showy growth of e.g. feathers or skin on the head of a bird or other animal
	(heraldry) in medieval times, an emblem used to decorate a helmet
	the center of a cambered road
	the top line of a hill, mountain, or wave
	the top or extreme point of something (usually a mountain or hill)

top out (verb)	crest (verb)
to reach the highest point; attain maximum intensity, activity	reach a high point
provide with a top or finish the top (of a structure)	lie at the top of
give up one's career just as one becomes very successful