soccer player vs athlete

soccer player and athlete both are nouns.

Word	Noun	Adjective	Verb	Adverb
soccer player	Yes	No	No	No
athlete	Yes	No	No	No

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

Other hypernyms of soccer player include jock, participant, player.

soccer player (noun)	athlete (noun)
an athlete who plays soccer	a person trained to compete in sports