Christiania vs national capital

Christiania and national capital both are nouns.

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

Christiania (noun)	national capital (noun)
the capital and largest city of Norway; the country's main port; located at the head of a fjord on Norway's southern coast	the capital city of a nation