player vs role player

player and role player both are nouns.

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

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

Other synonyms of player include actor, histrion, thespian.

player (noun)	role player (noun)
a theatrical performer	a theatrical performer
a person who participates in or is skilled at some game	a person who makes deceitful pretenses
someone who plays a music as a profession
a person who pursues a number of different social and sexual partners simultaneously
someone who takes part in an activity