urban center vs Sao Louis

urban center and Sao Louis both are nouns.

Word	Noun	Adjective	Verb	Adverb
urban center	Yes	No	No	No
Sao Louis	Yes	No	No	No

urban center (noun)	Sao Louis (noun)
a large and densely populated urban area; may include several independent administrative districts	a city on an offshore island in northeast Brazil