national capital vs capital of Barbados

national capital and capital of Barbados both are nouns.

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

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