Maritime Provinces vs The Maritimes

Maritime Provinces and The Maritimes both are nouns.

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

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

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

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

Maritime Provinces (noun)	The Maritimes (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