Saint John's vs capital of Antigua and Barbuda

Saint John's and capital of Antigua and Barbuda both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint John's	Yes	No	No	No
capital of Antigua and Barbuda	Yes	No	No	No

As nouns, Saint John's and capital of Antigua and Barbuda are synonyms defined as:

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

Other synonyms of Saint John's include St. John's.

Saint John's (noun)	capital of Antigua and Barbuda (noun)
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