Ground Zero vs Greater New York

Ground Zero and Greater New York both are nouns.

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

Ground Zero (noun)	Greater New York (noun)
the site of the World Trade Center before it was destroyed	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