crest vs brow

crest and brow both are nouns.

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

As nouns, brow is a hyponym of crest; that is, brow is a word with a more specific, narrower meaning than crest:

Other hyponyms of crest include hilltop, pinnacle, mountain peak.

crest (noun)	brow (noun)
a showy growth of e.g. feathers or skin on the head of a bird or other animal	the part of the face above the eyes
(heraldry) in medieval times, an emblem used to decorate a helmet	the arch of hair above each eye
the center of a cambered road	the peak of a hill
the top line of a hill, mountain, or wave
the top or extreme point of something (usually a mountain or hill)

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