Diomedea nigripes vs mollymawk

Diomedea nigripes and mollymawk both are nouns.

Word	Noun	Adjective	Verb	Adverb
Diomedea nigripes	Yes	No	No	No
mollymawk	Yes	No	No	No

As nouns, mollymawk is a hypernym of Diomedea nigripes; that is, mollymawk is a word with a broader meaning than Diomedea nigripes:

Diomedea nigripes: a variety of albatross with black feet
mollymawk: large web-footed birds of the Southern Hemisphere having long narrow wings; noted for powerful gliding flight

Other hypernyms of Diomedea nigripes include albatross.

Diomedea nigripes (noun)	mollymawk (noun)
a variety of albatross with black feet	large web-footed birds of the Southern Hemisphere having long narrow wings; noted for powerful gliding flight