Saint Martin vs St. Maarten

Saint Martin and St. Maarten both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Martin	Yes	No	No	No
St. Maarten	Yes	No	No	No

As nouns, Saint Martin and St. Maarten are synonyms defined as:

Saint Martin and St. Maarten: an island in the western Leeward Islands; administered jointly by France and the Netherlands

Other synonyms of Saint Martin include Saint Maarten, Sint Maarten, St. Martin.

Saint Martin (noun)	St. Maarten (noun)
an island in the western Leeward Islands; administered jointly by France and the Netherlands	an island in the western Leeward Islands; administered jointly by France and the Netherlands