player vs contestant

player and contestant both are nouns.

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

As nouns, contestant is a hypernym of player; that is, contestant is a word with a broader meaning than player:

player (noun)	contestant (noun)
a theatrical performer	a person who participates in competitions
a person who participates in or is skilled at some game	a person who dissents from some established policy
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