urban center vs Astrakhan

urban center and Astrakhan both are nouns.

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

urban center (noun)	Astrakhan (noun)
a large and densely populated urban area; may include several independent administrative districts	a city in southwestern Russia on the delta of the Volga River