urban center vs Mannheim

urban center and Mannheim both are nouns.

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

urban center (noun)	Mannheim (noun)
a large and densely populated urban area; may include several independent administrative districts	a city in southwestern Germany at the confluence of the Rhine and Neckar rivers