scaup vs scaup duck

scaup and scaup duck both are nouns.

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

As nouns, scaup and scaup duck are synonyms defined as:

scaup and scaup duck: diving ducks of North America having a bluish-grey bill

Other synonyms of scaup include bluebill, broadbill.

scaup (noun)	scaup duck (noun)
diving ducks of North America having a bluish-grey bill	diving ducks of North America having a bluish-grey bill