Atlantic Ocean vs Gulf of Mexico

Atlantic Ocean and Gulf of Mexico both are nouns.

Word	Noun	Adjective	Verb	Adverb
Atlantic Ocean	Yes	No	No	No
Gulf of Mexico	Yes	No	No	No

Atlantic Ocean (noun)	Gulf of Mexico (noun)
the 2nd largest ocean; separates North and South America on the west from Europe and Africa on the east	an arm of the Atlantic to the south of the United States and to the east of Mexico