urban center vs Koln

urban center and Koln both are nouns.

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

urban center (noun)	Koln (noun)
a large and densely populated urban area; may include several independent administrative districts	a commercial center and river port in western Germany on the Rhine River; flourished during the 15th century as a member of the Hanseatic League