national capital vs Tarabulus Al-Gharb

national capital and Tarabulus Al-Gharb both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
Tarabulus Al-Gharb	Yes	No	No	No

national capital (noun)	Tarabulus Al-Gharb (noun)
the capital city of a nation	the capital and chief port and largest city of Libya; in northwestern Libya on the Mediterranean Sea; founded by the Phoenicians in the 7th century BC