The article touched on it briefly, but the main difference between the two is ideology. Hitler had rather extreme views on race and religion that dominated his policies, and forced the mass slaughter of millions. Trump's views might appear just as extreme, but they're rooted in his own ego, not his ideology. He is a White supremacist, yes, but not necessarily because he believes all Whites are superior. It's because he is White, so he must be superior and the rest of them come along for the ride, as long as they think like him. It also enables his movement to potentially embrace anyone, regardless of background, even people from backgrounds he disparages; all you have to do is pledge loyalty to Him, and you are in. You become "one of the good ones", as long as you can ignore the occasional casual racism and misogyny.
Think of the Trump employees during the trial who spoke about how the Trump Org was a big family and they felt valued there, even while corroborating the State's evidence against him? I think they did that on purpose, because they know as long as you flatter him he will tune out the rest.
Trump's ideology is centered only on himself. So, politically, this makes him a bit harder to pin down. He can take multiple policy positions at once, sometimes contradictory, and as long as he is at the center of it all they are all logically consistent as far as he is concerned. And it takes effort to find all those inconsistencies. Why not just accept what he has to say?