There's hundreds of discussions on this sub about this but every time it comes up I just like to link David Chandler's bit on it in his work The Campaigns of Napoleon as I think it deals with it the most concisely:

Since the 1940s it has been fashionable in some quarters to compare Napoleon with Hitler. Nothing could be more degrading to the former and more flattering to the latter. The comparison is odious. On the whole Napoleon was inspired (in the early years at least) by a noble dream, wholly dissimilar from Hitler’s vaunted but stillborn “New Order.” Napoleon left great and lasting testimonies to his genius—in codes of law and national identities which survive to the present day. Adolf Hitler left nothing but destruction.

In certain superficial aspects, however, the careers of the two men bear resemblances. Both climbed to power through the use of opportunism in an unsettled period that favored the emergence of adventurers and dictators. Both possessed that magnetic appeal of personality that inspired their devotees. Both overthrew an older society, created new laws in an attempt to set up a new social order, challenged the position of the churches, resorted to police-state terror and atrocities to gain ends; both proved incapable of converting a conquered continent into a lasting Napoleonic Empire or a Thousand Year Reich.

But there the resemblance abruptly ends. Even though it is difficult to form an objective view of Hitler in our own time, there can be no doubt that he was not cast in the same mold as Napoleon. Despite flashes of lucky intuition, Hitler was no soldier. Hitler’s most lasting perverted achievement for which he will be remembered to the end of history was genocide; Napoleon will always be regarded as a soldier of genius and the creator of modern Europe. The two most devastating “corporals” of modern history therefore have little in common. In the words of Octave Aubry: “This is his [Napoleon’s] distinction, and, if necessary, his excuse. When an achievement lasts so long and bears such fruit, it provides its own justification.”20

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There is all this, of course. But there is also the fact that they both tried (and failed) to invade something that looked like Russia.