lineman vs football player

lineman and football player both are nouns.

Word	Noun	Adjective	Verb	Adverb
lineman	Yes	No	No	No
football player	Yes	No	No	No

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

Other hypernyms of lineman include footballer.

lineman (noun)	football player (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