unexpressive vs impassive

unexpressive and impassive both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unexpressive	No	Yes	No	No
impassive	No	Yes	No	No

As adjectives, unexpressive and impassive are synonyms defined as:

Other synonyms of unexpressive include deadpan, expressionless, poker-faced.

unexpressive (adjective)	impassive (adjective)
deliberately impassive in manner	deliberately impassive in manner
	having or revealing little emotion or sensibility; not easily aroused or excited