unexpressive vs expressionless

unexpressive and expressionless both are adjectives.

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

As adjectives, unexpressive and expressionless are synonyms defined as:

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

unexpressive (adjective)	expressionless (adjective)
deliberately impassive in manner	deliberately impassive in manner