national capital vs Basseterre

national capital and Basseterre both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
Basseterre	Yes	No	No	No

national capital (noun)	Basseterre (noun)
the capital city of a nation	the capital of Saint Kitts and Nevis on the island of Saint Christopher