Larus marinus vs black-backed gull

Larus marinus and black-backed gull both are nouns.

Word	Noun	Adjective	Verb	Adverb
Larus marinus	Yes	No	No	No
black-backed gull	Yes	No	No	No

As nouns, Larus marinus and black-backed gull are synonyms defined as:

Larus marinus and black-backed gull: white gull having a black back and wings

Other synonyms of Larus marinus include cob, great black-backed gull.

Larus marinus (noun)	black-backed gull (noun)
white gull having a black back and wings	white gull having a black back and wings