tennis player vs player

tennis player and player both are nouns.

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

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

Other hypernyms of tennis player include athlete, jock, participant.

tennis player (noun)	player (noun)
an athlete who plays tennis	a theatrical performer
	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