Dennis Prager : Why Doesn't Communism Have as Bad a Name as Nazism?

Why is it that when people want to describe particularly evil individuals or regimes, they use the terms "Nazi" or "Fascist" but almost never "Communist?"

Given the amount the human suffering Communists have caused - 70 million killed in China, 20-30 million in the former Soviet Union, and almost one-third of all Cambodians; the decimation of Tibetan and Chinese culture; totalitarian enslavement of North Koreans, Chinese, Vietnamese, and Russians; a generation deprived of human rights in Cuba; and much more -- why is "Communist" so much less a term of revulsion than "Nazi?"