lineman vs guard

lineman and guard both are nouns.

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

As nouns, guard is a hyponym of lineman; that is, guard is a word with a more specific, narrower meaning than lineman:

lineman: (American football) the position of a player on a football team who is stationed on the line of scrimmage
guard: (American football) a position on the line of scrimmage between the center and the tackles

Other hyponyms of lineman include center, centre, tackle, end.

As nouns, guard is a hyponym of lineman; that is, guard is a word with a more specific, narrower meaning than lineman:

lineman: one of the players on the line of scrimmage
guard: the person who lines up between the center and the tackles on the offensive line of a football team on the line of scrimmage

Other hyponyms of lineman include center, centre, snapper, end, tackle.

lineman (noun)	guard (noun)
(American football) the position of a player on a football team who is stationed on the line of scrimmage	a position on a basketball team
one of the players on the line of scrimmage	the duty of serving as a sentry
a person who installs or repairs electrical or telephone lines	(American football) a position on the line of scrimmage between the center and the tackles
the surveyor who marks positions with a range pole	a precautionary measure warding off impending danger or damage or injury etc.
	a device designed to prevent injury or accidents
	a posture of defence in boxing or fencing
	a military unit serving to protect some place or person
	the person who lines up between the center and the tackles on the offensive line of a football team on the line of scrimmage
	a person who keeps watch over something or someone
	the person who plays the position of guard on a basketball team

lineman (verb)	guard (verb)
	watch over or shield from danger or harm; protect
	protect against a challenge or attack
	to keep watch over
	take precautions in order to avoid some unwanted consequence