greater scaup vs scaup

greater scaup and scaup both are nouns.

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

As nouns, scaup is a hypernym of greater scaup; that is, scaup 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
scaup: diving ducks of North America having a bluish-grey bill

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

greater scaup (noun)	scaup (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