horseback riding vs athletics

horseback riding and athletics both are nouns.

Word	Noun	Adjective	Verb	Adverb
horseback riding	Yes	No	No	No
athletics	Yes	No	No	No

As nouns, athletics is a hypernym of horseback riding; that is, athletics is a word with a broader meaning than horseback riding:

horseback riding: the sport of sitting on the back of a horse while controlling its movements
athletics: an active diversion requiring physical exertion and competition

Other hypernyms of horseback riding include sport.

horseback riding (noun)	athletics (noun)
travel by being carried on horseback	an active diversion requiring physical exertion and competition
the sport of sitting on the back of a horse while controlling its movements	participation in sports events as an extracurricular activity
	a contest between athletes