Aythya marila vs scaup duck

Aythya marila and scaup duck both are nouns.

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

As nouns, scaup duck is a hypernym of Aythya marila; that is, scaup duck is a word with a broader meaning than Aythya marila:

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

Other hypernyms of Aythya marila include bluebill, broadbill, scaup.

Aythya marila (noun)	scaup duck (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