urban center vs Palermo

urban center and Palermo both are nouns.

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

urban center (noun)	Palermo (noun)
a large and densely populated urban area; may include several independent administrative districts	the capital of Sicily; located in northwestern Sicily; an important port for 3000 years