There's no reason to believe Hitler would emerge dictator or even a politician; there's no reason he would even venture in that direction in the first place. He might still be a, well, violent person depending on whether you trust some studies, but the Hitler of OTL -- an antisemite, a populist, and a fascist -- emerged largely due to circumstances present in his native Germany. The power and ideological vacuum of Eastern and Central Europe - wherein it was believed by certain segments of society that both liberal democracy and monarchy were discredited, tearing apart the carefully crafted veneer where revanchism and genocide were supposed to be under a curtain of sorts - simply did not exist in the United States, which emerged in the postwar years very prosperous. The most that can be said is Hitler emerges a sort of Huey Long, running on a demagoguic platform; whether, of course, he might extend this to a national level is very much debatable.
As for Germany, it would certainly end up very differently. The German Workers' Party (not even the NSDAP, which was almost purely Hitler's creation) would likely fade into obscurity; it was Hitler and his 'talents' that brought attention to the party in the first place. I don't see the KPD, who simply lacked the sheer resources necessary to overcome the German military-industrial complex whose alliance with Hitler put him into power, filling the vacuum of fascism. More likely, Germany emerges in the mid-1930s a redressed version of its 1916-1918 self; a right-wing dictatorship empowered by the military and the industrialists, even if without the titular monarch. World War II would almost certainly happened (the opinions of German Junkers towards Hitler were based on the grounds that he was too vulgar; antisemitism and the stab-in-the-back myth had already found itself as the religion of ruling circles), though whether it would happen in 1939 is debatable. Perhaps we see a World War II that starts in the 1940s, which I think would certainly have notable effects on the world.