crest vs top side

crest and top side both are nouns.

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

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

Other hypernyms of crest include top, upper side, upside.

crest (noun)	top side (noun)
a showy growth of e.g. feathers or skin on the head of a bird or other animal	the highest or uppermost side of anything
(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)

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