posted by Helena .
does anyone know what a megacity is and which cities are a megacity and a millionaire city and which are a millionaire city.
Since this is not my area of expertise, I searched Google under the key words "megacity 'millionaire city' difference" to get this:
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.