national capital vs capital of Latvia

national capital and capital of Latvia both are nouns.

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

national capital (noun)	capital of Latvia (noun)
the capital city of a nation	a port city on the Gulf of Riga that is the capital and largest city of Latvia; formerly a member of the Hanseatic League