pewit vs sea gull

pewit and sea gull both are nouns.

Word	Noun	Adjective	Verb	Adverb
pewit	Yes	No	No	No
sea gull	Yes	No	No	No

As nouns, sea gull is a hypernym of pewit; that is, sea gull is a word with a broader meaning than pewit:

pewit: small black-headed European gull
sea gull: mostly white aquatic bird having long pointed wings and short legs

Other hypernyms of pewit include gull, seagull.

pewit (noun)	sea gull (noun)
large crested Old World plover having wattles and spurs	mostly white aquatic bird having long pointed wings and short legs
small olive-colored woodland flycatchers of eastern North America
small black-headed European gull