human face vs visage

human face and visage both are nouns.

Word	Noun	Adjective	Verb	Adverb
human face	Yes	No	No	No
visage	Yes	No	No	No

As nouns, visage is a hyponym of human face; that is, visage is a word with a more specific, narrower meaning than human face:

human face: the front of the human head from the forehead to the chin and ear to ear
visage: the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)

Other hyponyms of human face include countenance, kisser, mug, phiz, physiognomy, smiler.

human face (noun)	visage (noun)
the front of the human head from the forehead to the chin and ear to ear	the appearance conveyed by a person's face
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)