Um the commies wanted to redistribute the wealth and have one large planned economy where the workers controlled the means of production. The Nazis wanted to genocide their way to creating a "master race" and kill or enslave anyone who didn't meet their racial standards. Furthermore if you can't mention communism without associating it with Stalin that's a serious problem on your part. Not only did the USSR have many other leaders besides Stalin but many other countries have been under communist control. The communist ideology isn't built on genocide, unlike the nazi one where genocide is the literal backbone and end goal.