role player vs impostor

role player and impostor both are nouns.

Word	Noun	Adjective	Verb	Adverb
role player	Yes	No	No	No
impostor	Yes	No	No	No

As nouns, role player and impostor are synonyms defined as:

Other synonyms of role player include fake, faker, fraud, imposter, pretender, pseud, pseudo, sham, shammer.

role player (noun)	impostor (noun)
a theatrical performer	a person who makes deceitful pretenses
a person who makes deceitful pretenses