poster vs Equus caballus

poster and Equus caballus both are nouns.

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

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

poster: a horse kept at an inn or post house for use by mail carriers or for rent to travelers
Equus caballus: solid-hoofed herbivorous quadruped domesticated since prehistoric times

Other hypernyms of poster include horse.

poster (noun)	Equus caballus (noun)
a horse kept at an inn or post house for use by mail carriers or for rent to travelers	solid-hoofed herbivorous quadruped domesticated since prehistoric times
a sign posted in a public place as an advertisement
someone who pastes up bills or placards on walls or billboards