Luxemburg vs national capital

Luxemburg and national capital both are nouns.

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

Luxemburg (noun)	national capital (noun)
a grand duchy (a constitutional monarchy) landlocked in northwestern Europe between France and Belgium and Germany; an international financial center	the capital city of a nation
the capital and largest city of Luxembourg