fulmar vs petrel

fulmar and petrel both are nouns.

Word	Noun	Adjective	Verb	Adverb
fulmar	Yes	No	No	No
petrel	Yes	No	No	No

As nouns, petrel is a hypernym of fulmar; that is, petrel is a word with a broader meaning than fulmar:

fulmar: heavy short-tailed oceanic bird of polar regions
petrel: relatively small long-winged tube-nosed bird that flies far from land

fulmar (noun)	petrel (noun)
heavy short-tailed oceanic bird of polar regions	relatively small long-winged tube-nosed bird that flies far from land