lesser scaup vs lesser scaup duck

lesser scaup and lesser scaup duck both are nouns.

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

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

lesser scaup and lesser scaup duck: common scaup of North America; males have purplish heads

Other synonyms of lesser scaup include Aythya affinis, lake duck.

lesser scaup (noun)	lesser scaup duck (noun)
common scaup of North America; males have purplish heads	common scaup of North America; males have purplish heads