I'll end the argument right now. Here's a quote from Eugene Wigner, a Nobel-prize winning physicist who was friends with both Einstein and Von Neumann:
"I have known a great many intelligent people in my life. I knew Planck, von Laue and Heisenberg. Paul Dirac was my brother in law; Leo Szilard and Edward Teller have been among my closest friends; and Albert Einstein was a good friend, too. But none of them had a mind as quick and acute as Jancsi [John] von Neumann. I have often remarked this in the presence of those men and no one ever disputed.
But Einstein's understanding was deeper even than von Neumann's. His mind was both more penetrating and more original than von Neumann's. And that is a very remarkable statement. Einstein took an extraordinary pleasure in invention. Two of his greatest inventions are the Special and General Theories of Relativity; and for all of Jancsi's brilliance, he never produced anything as original."
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In terms of precocious, “gee whiz he can calculate Pi to the 23,000th decimal place in his head!” Johnny was unmatched. Nobody - for the exception of Ramanujan, whose talents in mathematics were unparalleled - could match Johnny’s eidetic gifts. But that raises an interesting question about what we mean by “intelligence.”
Both men were incredibly prolific. Von Neumann was an incredible polymath (everything from game theory in economics to computational engineering, pure & applied mathematics, etc.) but he didn’t revolutionize an entire field like Einstein did. What Einstein accomplished hadn’t been done in 250 years, and that was just one of his many gifts to humanity. Neumann’s mind was quicker than anybody of his era, but Einstein’s mind was both more penetrating and more original than Johnny’s- and that isn’t an indictment of Johnny, but a reminder of how incredible Einstein’s accomplishments were.