Hitler is a popular muggle analogy for Voldemort - but that comparison really undersells the terror Voldemort induced.

Voldemort has long been comparted to Hitler - Magical Hitler, Wizarding Hitler, etc. Voldemort and Hitler share many qualities: they both purport to be concerned for the dilution of "pure" race, they are both power hungry, and both lead organisations intent on persecuting those they deemed lesser. The comparison between Voldemort and Hitler has, clearly, real merit.

However, the two differ in a very important way. Hitler was at the head of a apparatus that waged war on the world - but he himself was not that apparatus. He did not fire a weapon on the front line, or sail a U-boat, or pilot a bomber. He was not personally responsible for almost any of the deaths that made up WW2, though he of course rightly assumes much of the blame for them. During WW2, Hitler must have been hated and reviled by those he sought to destroy but very few people personally feared him; people feared the German war machine in general but no one (to my knowledge) speaks of a deep, personal fear of Hitler himself.

Voldemort, in many ways, WAS the war machine that sought to uproot wizarding society. People feared the death eaters and werewolves and the giants - but they also feared Voldemort the individual. Magic allows for one man to personally affect a conflict on level impossible in our world. No one needed to fear that speaking Hitler's name would bring a missile down onto their heads. However, that was a very real fear during the wars Voldemort waged. Wizards and witches personally knew people - friends and family - that were killed by Voldemort himself! He was everywhere, they couldn't step out of their front door without checking the proverbial peephole first.

I think that this personalisation that Voldemort brought to his conflicts made him an altogether different beast from Hitler. For all of Hitler's evils, he was but a man. Voldemort, through his ruthlessness and personal touch, was something more.

For me, Voldemort is much closer to the Devil or any archetypal Boogeyman than he is to Hitler - and I think that this view fits with the themes and plot of the series. Voldemort was desperate to prove to everyone that he was more than a man and everyone believed him (except Dumbledore and a few others). At the culmination of the story, when Voldemort has everything he ever wanted in his grasp, Harry shows the world that Voldemort is indeed a man, and that he can die like one.

Thanks for reading, please let me know what you think.

EDIT: People are perhaps misunderstanding my point. I am not comparing the overall damage that each were responsible for. Clearly, WW2 involved many more people and many more atrocities than the wizarding wars. I do not think that that makes Hitler necessarily any more evil - he just had a more industrious war engine under him. I comparing the impressions that the people affected in the war had of Hitler and Voldemort and am saying that Voldemort was personally feared to a supernatural degree whilst Hitler was not.

EDIT 2: I think it should be clear in my post that I do not mean to compare the two, I am merely reacting to a comparison I have seen often in the fandom. I do not think it is fair to say that just because Voldemort isn't real and Hitler is that they can't be compared - the point of fiction is that we take the themes presented seriously and explore them.