Greater London vs Harley Street

Greater London and Harley Street both are nouns.

Word	Noun	Adjective	Verb	Adverb
Greater London	Yes	No	No	No
Harley Street	Yes	No	No	No

Greater London (noun)	Harley Street (noun)
the capital and largest city of England; located on the Thames in southeastern England; financial and industrial and cultural center	a street in central London where the consulting rooms of many physicians and surgeons are located