national capital vs capital of Antigua and Barbuda

national capital and capital of Antigua and Barbuda both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
capital of Antigua and Barbuda	Yes	No	No	No

national capital (noun)	capital of Antigua and Barbuda (noun)
the capital city of a nation	the capital and largest city of Antigua and Barbuda; located on the island of Antigua