St. John's vs Saint John's

St. John's and Saint John's both are nouns.

Word	Noun	Adjective	Verb	Adverb
St. John's	Yes	No	No	No
Saint John's	Yes	No	No	No

As nouns, St. John's and Saint John's are synonyms defined as:

St. John's and Saint John's: a port and provincial capital of Newfoundland

As nouns, St. John's and Saint John's are synonyms defined as:

St. John's and Saint John's: the capital and largest city of Antigua and Barbuda; located on the island of Antigua

Other synonyms of St. John's include capital of Antigua and Barbuda.

St. John's (noun)	Saint John's (noun)
a port and provincial capital of Newfoundland	a port and provincial capital of Newfoundland
the capital and largest city of Antigua and Barbuda; located on the island of Antigua	the capital and largest city of Antigua and Barbuda; located on the island of Antigua