national capital vs capital of Argentina

national capital and capital of Argentina both are nouns.

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

national capital (noun)	capital of Argentina (noun)
the capital city of a nation	capital and largest city of Argentina; located in eastern Argentina near Uruguay; Argentina's chief port and industrial and cultural center