Greater New York vs Ground Zero

Greater New York and Ground Zero both are nouns.

Word	Noun	Adjective	Verb	Adverb
Greater New York	Yes	No	No	No
Ground Zero	Yes	No	No	No

Greater New York (noun)	Ground Zero (noun)
the largest city in New York State and in the United States; located in southeastern New York at the mouth of the Hudson river; a major financial and cultural center	the site of the World Trade Center before it was destroyed