national capital vs Helsingfors

national capital and Helsingfors both are nouns.

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

national capital (noun)	Helsingfors (noun)
the capital city of a nation	the capital and largest city of Finland; located in southern Finland; a major port and commercial and cultural center