The Watch Tower leadership certainly acts in a manner that resembles totalitarian states, in which information is controlled and members are stirred into activity to pursue a common goal achieved through unity of thinking. They clearly identify their enemies and encourage members to hate them. They also require unquestioning obedience.
It's an ideology, a belief generated by the cultish conviction that they alone are God's "organisation" and are acting on God's instructions.
Hitler had a worldview as well, but it was driven by a maniacal belief that Jews were the cause of the world's evils. He saw them as inhuman beasts and had no conscience about exterminating them en masse. There's the difference.
I'm reading a chilling book at the moment, Saul Friedlander's Nazi Germany and the Jews, which includes accounts of the cold and dispasionate mass murder of tens of thousands of Jews at a time in 1941: men and women alike were ordered to strip naked, lie face-down in a pit or on top of dead or dying Jews before they were shot with a single bullet to the head from a distance of two metres. The soldiers worked in long shifts to carry out their work.
As much as I hate the WTS, I would never suggest that they would do the same. There's a limit to Star Tiger's analogy, but there are certainly some common elements.