footballer vs athlete

footballer and athlete both are nouns.

Word	Noun	Adjective	Verb	Adverb
footballer	Yes	No	No	No
athlete	Yes	No	No	No

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

Other hypernyms of footballer include jock, participant, player.

footballer (noun)	athlete (noun)
an athlete who plays American football	a person trained to compete in sports