greater scaup vs bluebill

greater scaup and bluebill both are nouns.

Word	Noun	Adjective	Verb	Adverb
greater scaup	Yes	No	No	No
bluebill	Yes	No	No	No

As nouns, bluebill is a hypernym of greater scaup; that is, bluebill is a word with a broader meaning than greater scaup:

greater scaup: large scaup of North America having a greenish iridescence on the head of the male
bluebill: diving ducks of North America having a bluish-grey bill

Other hypernyms of greater scaup include broadbill, scaup, scaup duck.

greater scaup (noun)	bluebill (noun)
large scaup of North America having a greenish iridescence on the head of the male	diving ducks of North America having a bluish-grey bill