There have been between 25,000,000 to 40,000,000 million killed by Communist and only about 7,000,000 killed by Nazi.==
Nazi killed at keast 6 mln in only one Poland. So they killed far more then 7 mlns all together. Accually we need to calculate all victimes thoroughly.
You are right about which one is worse. But there is one more, much more fundamental, difference: communism is a way of life, while nazism is an ideology and not per se a way of life. The word "communism" is also used to denote an ideology, and this practice gives rise to unnecessary confusion.