grimace vs screw up

grimace is a noun but screw up is not a noun.

Word	Noun	Adjective	Verb	Adverb
grimace	Yes	No	Yes	No
screw up	No	No	Yes	No

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

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

grimace (noun)	screw up (noun)
a contorted facial expression

grimace (verb)	screw up (verb)
contort the face to indicate a certain mental or emotional state	twist into a strained configuration
	make more intense
	screw or turn higher
	make a mess of, destroy or ruin