blackcap vs seagull

blackcap and seagull both are nouns.

Word	Noun	Adjective	Verb	Adverb
blackcap	Yes	No	No	No
seagull	Yes	No	No	No

As nouns, seagull is a hypernym of blackcap; that is, seagull is a word with a broader meaning than blackcap:

Other hypernyms of blackcap include gull, sea gull.

blackcap (noun)	seagull (noun)
small brownish-grey warbler with a black crown	mostly white aquatic bird having long pointed wings and short legs
chickadee having a dark crown
small black-headed European gull
raspberry native to eastern North America having black thimble-shaped fruit