Philadelphia vs urban center

Philadelphia and urban center both are nouns.

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

Philadelphia (noun)	urban center (noun)
the largest city in Pennsylvania; located in the southeastern part of the state on the Delaware river; site of Independence Hall where the Declaration of Independence and the Constitution were signed; site of the University of Pennsylvania	a large and densely populated urban area; may include several independent administrative districts