urban center vs Greenville

urban center and Greenville both are nouns.

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

urban center (noun)	Greenville (noun)
a large and densely populated urban area; may include several independent administrative districts	a town in northwest South Carolina in the Piedmont
	a town in western Mississippi on the Mississippi River to the north of Vicksburg
	a city in eastern North Carolina; tobacco market