urban center vs Billings

urban center and Billings both are nouns.

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

urban center (noun)	Billings (noun)
a large and densely populated urban area; may include several independent administrative districts	the largest city in Montana; located in southern Montana on the Yellowstone river