city vs Sao Paulo

city and Sao Paulo both are nouns.

Word	Noun	Adjective	Verb	Adverb
city	Yes	No	No	No
Sao Paulo	Yes	No	No	No

city (noun)	Sao Paulo (noun)
people living in a large densely populated municipality	an ultramodern city in southeastern Brazil; the largest city in South America
a large and densely populated urban area; may include several independent administrative districts
an incorporated administrative district established by state charter