pony vs racehorse

pony and racehorse both are nouns.

Word	Noun	Adjective	Verb	Adverb
pony	Yes	No	No	No
racehorse	Yes	No	No	No

As nouns, racehorse is a hypernym of pony; that is, racehorse is a word with a broader meaning than pony:

Other hypernyms of pony include bangtail, race horse.

pony (noun)	racehorse (noun)
any of various breeds of small gentle horses usually less than five feet high at the shoulder	a horse bred for racing
a range horse of the western United States
an informal term for a racehorse
a small glass adequate to hold a single swallow of whiskey
a literal translation used in studying a foreign language (often used illicitly)