poker face vs visage

poker face and visage both are nouns.

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

As nouns, visage is a hypernym of poker face; that is, visage is a word with a broader meaning than poker face:

poker face: a face without any interpretable expression (as that of a good poker player)
visage: the appearance conveyed by a person's face

Other hypernyms of poker face include countenance.

poker face (noun)	visage (noun)
a face without any interpretable expression (as that of a good poker player)	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)