Atlantic Ocean vs North Atlantic

Atlantic Ocean and North Atlantic both are nouns.

Word	Noun	Adjective	Verb	Adverb
Atlantic Ocean	Yes	No	No	No
North Atlantic	Yes	No	No	No

Atlantic Ocean (noun)	North Atlantic (noun)
the 2nd largest ocean; separates North and South America on the west from Europe and Africa on the east	that part of the Atlantic Ocean to the north of the equator