I don't think comparing communism with fasism, at least when it comes to exterminating ethnic minorities is accurate. this is an opinion shared by academics, including coauthors of "The Black Book of Communism" (the book which claims communism killed 80M-100M people, though the upper end of the range is the one which has more attention. this number is disputed, again also by coauthors)

I could explain why I believe you shouldn't do this in my own words, but I will use the words of Nicolas Werth, one of the three main coauthors who distanced themselves from the book:

Death camps did not exist in the Soviet Union.

and

The more you compare Communism and Nazism, the more the differences are obvious.

Another quote I will give is from Amir Weiner an American historian and associate professor of Soviet history at Stanford University who wrote:

[w]hen Stalin's successors opened the gates of the Gulag, they allowed 3 million inmates to return home. When the Allies liberated the Nazi death camps, they found thousands of human skeletons barely alive awaiting what they knew to be inevitable execution.

I sourced these quotes from Wikipedia: "The Black Book of Communism", references 19 and 14.

My point isn't to say the Soviet Union, or other states which had or have Marxist-Leninist governments are without critique, but that comparing them to the III Reich, at the very least diminishes the crimes committed by Nazis and makes analysis of the aforementioned States more muddy.