Number of reasons why you're wrong:
Hitler was Nazi-German, Thanos was purple.
Hitler commited suicide, Thanos died twice: Head chopped off and Iron Man snap.
Hitler had hair and a mustache. Thanos had a wrinkly "beard".
Hitler took tried to take over Europe. Thanos tried to wipe out half of life in the universe.
Hitler only slaughtered jews for no reason. Thanos at least spared a few to call his children.
Hitler wasn't power-hungry enough to hunt for infinity stones and put them on a golden glove. Thanos did
Hitler was a scrawny man. Thanos is a mad purple titan.
Hitler wasn't an alien. Thanos is.
Hitler had death camps to kill off jews he captured. Thanos just hopped from planet to planet claiming that he saved them from an inevitable death by killing them.
Hitler never lost his home. Thanos did.
And while both of them were genocidal maniacs with an army at their fingertips, Hitler was a real person, while Thanos was a fictional character thought up of by a comic book creator.
