What is the difference between the imperial power of Diocletian and the power of Augustine?

Many historians say there was little difference between the two rulers. In my opinion, this is not the case. They were similar only in the desire to rule infinitely and cruelty towards the Republicans. Unlike Diocletian, Augustus sought support in the Senate, when the other made it so that the Senate could not influence policy in the state. Diocletian was vain, he enjoyed power, and all his subjects were in awe and fear of his cruelty.