facial expression vs visage

facial expression and visage both are nouns.

Word	Noun	Adjective	Verb	Adverb
facial expression	Yes	No	No	No
visage	Yes	No	No	No

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

Other hypernyms of facial expression include countenance.

facial expression (noun)	visage (noun)
the feelings expressed on a person's face	the appearance conveyed by a person's face
a gesture executed with the facial muscles	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)