urban center vs Osaka

urban center and Osaka both are nouns.

Word	Noun	Adjective	Verb	Adverb
urban center	Yes	No	No	No
Osaka	Yes	No	No	No

urban center (noun)	Osaka (noun)
a large and densely populated urban area; may include several independent administrative districts	port city on southern Honshu on Osaka Bay; a commercial and industrial center of Japan