urban center vs Salonica

urban center and Salonica both are nouns.

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

urban center (noun)	Salonica (noun)
a large and densely populated urban area; may include several independent administrative districts	a port city in northeastern Greece on an inlet of the Aegean Sea; second largest city of Greece