Business Insider: The key difference between billionaires and millionairesBy Business Insider. Published June 16, 2019. Updated June 16 at 12:40 pm Russia's wealthy elite look at yachts during the summer Millionaire Fair in Moscow on July 2, 2010. Photo by AFPMillionaires and billionaires may both be richer than the average person, but they’re each in a group of their own.Read more here.