Otis tarda vs bustard

Otis tarda and bustard both are nouns.

Word	Noun	Adjective	Verb	Adverb
Otis tarda	Yes	No	No	No
bustard	Yes	No	No	No

As nouns, bustard is a hypernym of Otis tarda; that is, bustard is a word with a broader meaning than Otis tarda:

Otis tarda: largest European land bird
bustard: large heavy-bodied chiefly terrestrial game bird capable of powerful swift flight; classified with wading birds but frequents grassy steppes

Otis tarda (noun)	bustard (noun)
largest European land bird	large heavy-bodied chiefly terrestrial game bird capable of powerful swift flight; classified with wading birds but frequents grassy steppes