capital of Barbados vs national capital

capital of Barbados and national capital both are nouns.

Word	Noun	Adjective	Verb	Adverb
capital of Barbados	Yes	No	No	No
national capital	Yes	No	No	No

capital of Barbados (noun)	national capital (noun)
capital of Barbados; a port city on the southwestern coast of Barbados	the capital city of a nation