Cervus unicolor vs deer

Cervus unicolor and deer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cervus unicolor	Yes	No	No	No
deer	Yes	No	No	No

As nouns, deer is a hypernym of Cervus unicolor; that is, deer is a word with a broader meaning than Cervus unicolor:

Cervus unicolor: a deer of southern Asia with antlers that have three tines
deer: distinguished from Bovidae by the male's having solid deciduous antlers

Other hypernyms of Cervus unicolor include cervid.

Cervus unicolor (noun)	deer (noun)
a deer of southern Asia with antlers that have three tines	distinguished from Bovidae by the male's having solid deciduous antlers