impassive vs unexpressive

impassive and unexpressive both are adjectives.

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

As adjectives, impassive and unexpressive are synonyms defined as:

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

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