polo pony vs Equus caballus

polo pony and Equus caballus both are nouns.

Word	Noun	Adjective	Verb	Adverb
polo pony	Yes	No	No	No
Equus caballus	Yes	No	No	No

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

polo pony: a small agile horse specially bred and trained for playing polo
Equus caballus: solid-hoofed herbivorous quadruped domesticated since prehistoric times

Other hypernyms of polo pony include horse.

polo pony (noun)	Equus caballus (noun)
a small agile horse specially bred and trained for playing polo	solid-hoofed herbivorous quadruped domesticated since prehistoric times