The comparison to Hitler is inevitable not because of death camps or body count, but because the foreign policy of Russia today seems to be on the same trajectory as the foreign policy of Nazi Germany prior to WW2.

Germany took Sudetenland from Czechoslovakia on the grounds that it was populated mostly by Germans, who were being oppressed by Slav-dominated government. Russia took Crimea from Ukraine on the grounds that it is populated mostly by Russians, who are being oppressed by the Ukrainian-dominated government.

Germany subsidized a Slovak separatist movement in Czechoslovakia, culminating in the declaration of independent Slovakia, which promptly became a German puppet state. Russia tried to do something similar with Donbas separatist, although it wasn't particularly successful.

Then, at last, Germany invaded what was left of Czechoslovakia, with intent to fully annex and absorb it. We're now watching Russia do the same to Ukraine.