auk vs seabird

auk and seabird both are nouns.

Word	Noun	Adjective	Verb	Adverb
auk	Yes	No	No	No
seabird	Yes	No	No	No

As nouns, seabird is a hypernym of auk; that is, seabird is a word with a broader meaning than auk:

auk: black-and-white short-necked web-footed diving bird of northern seas
seabird: a bird that frequents coastal waters and the open ocean: gulls, pelicans, gannets, cormorants, albatrosses, petrels, etc.

Other hypernyms of auk include sea bird, seafowl.

auk (noun)	seabird (noun)
black-and-white short-necked web-footed diving bird of northern seas	a bird that frequents coastal waters and the open ocean: gulls, pelicans, gannets, cormorants, albatrosses, petrels, etc.