hilltop vs crest

hilltop and crest both are nouns.

Word	Noun	Adjective	Verb	Adverb
hilltop	Yes	No	No	No
crest	Yes	No	Yes	No

As nouns, crest is a hypernym of hilltop; that is, crest is a word with a broader meaning than hilltop:

Other hypernyms of hilltop include crown, peak, summit, tip, top.

hilltop (noun)	crest (noun)
the peak of a hill	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)

hilltop (verb)	crest (verb)
	reach a high point
	lie at the top of