urban center vs Medellin

urban center and Medellin both are nouns.

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

urban center (noun)	Medellin (noun)
a large and densely populated urban area; may include several independent administrative districts	city in western Colombia; important coffee center