Why has communism killed more people than fascism?

I was browsing the website "revleft" and noticed the hammer and sickle all over the place. What exactly is the difference between having that on your site and having a swastika on your site? The amount of people that Hitler killed doesn't even begin to compare to the number dead after the fall of Stalin's regime. You really can't even say that it's because of the Nazi's racism and Antisemitism. First of all, the communists exterminated Jews, too. And liberals today have aligned themselves with extremists Muslims intent on killing Jews. Ironically, Muslims (Bosnian Muslims in particularly; also Saddam's uncle) aided and fought alongside Hitler. (many of them were in his army)