dawn horse vs Equus caballus

dawn horse and Equus caballus both are nouns.

Word	Noun	Adjective	Verb	Adverb
dawn horse	Yes	No	No	No
Equus caballus	Yes	No	No	No

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

dawn horse: earliest horse; extinct primitive dog-sized four-toed Eocene animal
Equus caballus: solid-hoofed herbivorous quadruped domesticated since prehistoric times

Other hypernyms of dawn horse include horse.

dawn horse (noun)	Equus caballus (noun)
earliest horse; extinct primitive dog-sized four-toed Eocene animal	solid-hoofed herbivorous quadruped domesticated since prehistoric times