Hitler is really quite a different thing. He created a cult, but in a very different way.
Hitler provided a national response and to many in Germany solutions to a very real crisis they were facing. Their country was collapsing in an catastrophic way. He was alone in offering any real tangible hope to the masses then. Not too many saw the monster he was about to become. Even King Edward VIII was sold on him. He never realised the monster that was about to be. Real issues, real time, real solutions, not just koolaid.
For some time he did a serious lot of good to his country. Most of all, he gave them hope for a better future which was just within their grasp. Life got better and became good for so many, no wonder they fell under his spell. If there were some thing people didn't quite agree with, well that was okay too. He was getting things done. Germany began to prosper, much more so than those other countries who only just survived the Great Depression.
Hitler offered real hope and solutions to real problems of the time. I remember a Polish descended work colleague who told me all the Poles used to come to their home as a child for parties and he heard so many of them say "Hitler wasn't so bad, at least he was getting rid of the Jews". Indicates that Jews weren't just a Nazi issue, not many Europeans liked them either. An inconvenient truth.
Hubbard and many other cults offer imaginary solutions to mainly imaginary problems. That's where they differ. If cult leaders rose to Hitler's position, they would be little different. Imagine the Gulags for SP's if Hubbard had his way, for example.
I have also noted that a number of ex scn's also run off to another cult of sorts, or create their own new one and I'm not going into that or talking names here at this time. To me, that indicates that they have ongoing issues that run a bit (or a lot) deeper than scientology. Unless they find an epiphany, they also become lost causes.
Scientology was just a diversion in their path to self destruction.