pewit gull vs Larus ridibundus

pewit gull and Larus ridibundus both are nouns.

Word	Noun	Adjective	Verb	Adverb
pewit gull	Yes	No	No	No
Larus ridibundus	Yes	No	No	No

As nouns, pewit gull and Larus ridibundus are synonyms defined as:

Other synonyms of pewit gull include blackcap, laughing gull, pewit.

pewit gull (noun)	Larus ridibundus (noun)
small black-headed European gull	small black-headed European gull