Mannheim vs urban center

Mannheim and urban center both are nouns.

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

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