billiard player vs participant

billiard player and participant both are nouns.

Word	Noun	Adjective	Verb	Adverb
billiard player	Yes	No	No	No
participant	Yes	No	No	No

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

Other hypernyms of billiard player include player.

billiard player (noun)	participant (noun)
someone who plays billiards	someone who takes part in an activity
	a person who participates in or is skilled at some game