national capital vs Pretoria

national capital and Pretoria both are nouns.

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

national capital (noun)	Pretoria (noun)
the capital city of a nation	city in the Transvaal; the seat of the executive branch of the government of South Africa