ass vs Equus asinus

ass and Equus asinus both are nouns.

Word	Noun	Adjective	Verb	Adverb
ass	Yes	No	No	No
Equus asinus	Yes	No	No	No

As nouns, Equus asinus is a hyponym of ass; that is, Equus asinus is a word with a more specific, narrower meaning than ass:

ass: hardy and sure-footed animal smaller and with longer ears than the horse
Equus asinus: domestic beast of burden descended from the African wild ass; patient but stubborn

Other hyponyms of ass include domestic ass, donkey, jack, jackass, jennet, jenny, jenny ass, wild ass.

ass (noun)	Equus asinus (noun)
slang for sexual intercourse	domestic beast of burden descended from the African wild ass; patient but stubborn
hardy and sure-footed animal smaller and with longer ears than the horse
the fleshy part of the human body that you sit on
a pompous fool