comportment vs mien

comportment and mien both are nouns.

Word	Noun	Adjective	Verb	Adverb
comportment	Yes	No	No	No
mien	Yes	No	No	No

As nouns, comportment and mien are synonyms defined as:

Other synonyms of comportment include bearing, presence.

comportment (noun)	mien (noun)
dignified manner or conduct	dignified manner or conduct