pull a face vs frown

pull a face is not a noun while frown is a noun.

Word	Noun	Adjective	Verb	Adverb
pull a face	No	No	Yes	No
frown	Yes	No	Yes	No

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

pull a face: 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 pull a face include squinch, squint, wince, smile, glower, lour, lower, screw up, mop, mow, pout.

pull a face (noun)	frown (noun)
	a facial expression of dislike or displeasure

pull a face (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