scaup vs Aythya marila

scaup and Aythya marila both are nouns.

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

As nouns, Aythya marila is a hyponym of scaup; that is, Aythya marila is a word with a more specific, narrower meaning than scaup:

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

Other hyponyms of scaup include greater scaup, Aythya affinis, lake duck, lesser scaup, lesser scaup duck.

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