urban center vs Tsaritsyn

urban center and Tsaritsyn both are nouns.

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

urban center (noun)	Tsaritsyn (noun)
a large and densely populated urban area; may include several independent administrative districts	a city in the European part of Russia on the Volga; site of German defeat in World War II in the winter of 1942-43