The Maritimes vs Maritime Provinces

The Maritimes and Maritime Provinces both are nouns.

Word	Noun	Adjective	Verb	Adverb
The Maritimes	Yes	No	No	No
Maritime Provinces	Yes	No	No	No

As nouns, The Maritimes and Maritime Provinces are synonyms defined as:

The Maritimes and Maritime Provinces: the collective name for the Canadian provinces of New Brunswick and Nova Scotia and Prince Edward Island

Other synonyms of The Maritimes include Canadian Maritime Provinces, Maritimes.

The Maritimes (noun)	Maritime Provinces (noun)
the collective name for the Canadian provinces of New Brunswick and Nova Scotia and Prince Edward Island	the collective name for the Canadian provinces of New Brunswick and Nova Scotia and Prince Edward Island