urban center vs Montreal

urban center and Montreal both are nouns.

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

urban center (noun)	Montreal (noun)
a large and densely populated urban area; may include several independent administrative districts	a city in southern Quebec province on the Saint Lawrence River; the largest city in Quebec and 2nd largest in Canada; the 2nd largest French-speaking city in the world