City of London vs the City

City of London and the City both are nouns.

Word	Noun	Adjective	Verb	Adverb
City of London	Yes	No	No	No
the City	Yes	No	No	No

As nouns, City of London and the City are synonyms defined as:

City of London and the City: the part of London situated within the ancient boundaries; the commercial and financial center of London

City of London (noun)	the City (noun)
the part of London situated within the ancient boundaries; the commercial and financial center of London	used to allude to the securities industry of Great Britain
	the part of London situated within the ancient boundaries; the commercial and financial center of London