lesser scaup duck vs Aythya affinis

lesser scaup duck and Aythya affinis both are nouns.

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

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

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

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

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