Opisthocomus vs bird genus

Opisthocomus and bird genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Opisthocomus	Yes	No	No	No
bird genus	Yes	No	No	No

As nouns, bird genus is a hypernym of Opisthocomus; that is, bird genus is a word with a broader meaning than Opisthocomus:

Opisthocomus (noun)	bird genus (noun)
type genus of the Opisthocomidae: hoatzins	a genus of birds