city vs St. Louis

city and St. Louis both are nouns.

Word	Noun	Adjective	Verb	Adverb
city	Yes	No	No	No
St. Louis	Yes	No	No	No

city (noun)	St. Louis (noun)
people living in a large densely populated municipality	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)
an incorporated administrative district established by state charter