national capital vs capital of Portugal

national capital and capital of Portugal both are nouns.

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

national capital (noun)	capital of Portugal (noun)
the capital city of a nation	capital and largest city and economic and cultural center of Portugal; a major port in western Portugal on Tagus River where it broadens and empties into the Atlantic