urban center vs Windy City

urban center and Windy City both are nouns.

Word	Noun	Adjective	Verb	Adverb
urban center	Yes	No	No	No
Windy City	Yes	No	No	No

urban center (noun)	Windy City (noun)
a large and densely populated urban area; may include several independent administrative districts	largest city in Illinois; a bustling Great Lakes port that extends 26 miles along the southwestern shoreline of Lake Michigan