Saint Louis vs urban center

Saint Louis and urban center both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Louis	Yes	No	No	No
urban center	Yes	No	No	No

Saint Louis (noun)	urban center (noun)
the largest city in Missouri; a busy river port on the Mississippi River near its confluence with the Missouri River; was an important staging area for wagon trains westward in the 19th century	a large and densely populated urban area; may include several independent administrative districts
king of France and son of Louis VIII; he led two unsuccessful Crusades; considered an ideal medieval king (1214-1270)