lineman vs footballer

lineman and footballer both are nouns.

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

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

Other hypernyms of lineman include football player.

lineman (noun)	footballer (noun)
(American football) the position of a player on a football team who is stationed on the line of scrimmage	an athlete who plays American football
one of the players on the line of scrimmage
a person who installs or repairs electrical or telephone lines
the surveyor who marks positions with a range pole