impassive vs expressionless

impassive and expressionless both are adjectives.

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

As adjectives, impassive and expressionless are synonyms defined as:

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

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