athletics vs tug-of-war

athletics and tug-of-war both are nouns.

Word	Noun	Adjective	Verb	Adverb
athletics	Yes	No	No	No
tug-of-war	Yes	No	No	No

As nouns, tug-of-war is a hyponym of athletics; that is, tug-of-war is a word with a more specific, narrower meaning than athletics:

athletics: a contest between athletes
tug-of-war: a contest in which teams pull of opposite ends of a rope; the team dragged across a central line loses

athletics (noun)	tug-of-war (noun)
an active diversion requiring physical exertion and competition	any hard struggle between equally matched groups
participation in sports events as an extracurricular activity	a contest in which teams pull of opposite ends of a rope; the team dragged across a central line loses
a contest between athletes