urban center vs Leiden

urban center and Leiden both are nouns.

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

urban center (noun)	Leiden (noun)
a large and densely populated urban area; may include several independent administrative districts	a city in the western Netherlands; residence of the Pilgrim Fathers for 11 years before they sailed for America in 1620