Differently and probably communist.
I don't think communist. With out WWII Russia wouldn't have modernised it's army as rapidly as it did. Also it would have had no chance to expand into eastern europe as I don't think the world would have been as patient with Russia as it was with Germany. Communist expansion in the east would have depended on how the Pacific war went (as it was at first completely unrelated to Europe), and as there wouldn't have been a war in Europe then both Britain and America would have been able to concentrate on the pacific. The Royal Navy in force could have made things very difficult for the Japanise and combined with the USN it wouldn't have taken quite so long to drive them back to the mainland. After Japan left mainland Asia the Russians may have attempted to help the spread of communism, but without the military hardware they developed and manufactured their support could only have been limited.
Then of course you have no WWII, no atomic bomb (as development of the A bomb was fueled by the war in Europe, no the Pacific).
So in my Opinion the world would be very different. But not over populated, and not communist.
