player vs card player

player and card player both are nouns.

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

As nouns, card player is a hyponym of player; that is, card player is a word with a more specific, narrower meaning than player:

player (noun)	card player (noun)
a theatrical performer	someone who plays (or knows how to play) card games
a person who participates in or is skilled at some game
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