protohippus vs Equus caballus

protohippus and Equus caballus both are nouns.

Word	Noun	Adjective	Verb	Adverb
protohippus	Yes	No	No	No
Equus caballus	Yes	No	No	No

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

protohippus: Pliocene horse approaching donkeys in size
Equus caballus: solid-hoofed herbivorous quadruped domesticated since prehistoric times

Other hypernyms of protohippus include horse.

protohippus (noun)	Equus caballus (noun)
Pliocene horse approaching donkeys in size	solid-hoofed herbivorous quadruped domesticated since prehistoric times