grimace vs frown

grimace and frown both are nouns.

Word	Noun	Adjective	Verb	Adverb
grimace	Yes	No	Yes	No
frown	Yes	No	Yes	No

As verbs, frown is a hyponym of grimace; that is, frown is a word with a more specific, narrower meaning than grimace:

grimace: contort the face to indicate a certain mental or emotional state
frown: look angry or sullen, wrinkle one's forehead, as if to signal disapproval

Other hyponyms of grimace include squinch, squint, wince, smile, glower, lour, lower, screw up, mop, mow, pout.

grimace (noun)	frown (noun)
a contorted facial expression	a facial expression of dislike or displeasure

grimace (verb)	frown (verb)
contort the face to indicate a certain mental or emotional state	look angry or sullen, wrinkle one's forehead, as if to signal disapproval