The "ethnic cleansing" of the Nazi regime was far more advanced in its ideology than the more localised instances seen in other parts of the world, as the Jews as a race would have been totally and utterly eradicated had Hitler achieved his aim of world domination and the 1000-year Reich had been established.
It is true that Serbs are not brought up en mass to believe Croats (or Bosnyaks) are inferior, sub-humans, a destructive bacillus within the human race that needs to be eradicated for the master race to be able to flourish - nor vice versa.
In this sense, I agree that Nazi ideology was 'more advanced' (i'd prefer to say 'more degraded') than the 'ideology' (such as it was, ie extreme nationalism) that underpinned such ethnic conflicts as we saw in the 1990s in former Yugoslavia.
However, communism - meaning some form of Marxist-Leninism - was yet 'more advanced' (using your terminology) than Nazism in the sense that
a) Clearly, if you weren't both Aryan, and prepared to subscribe to Nazi thinking on being Aryan, Nazism was bad news. This was true even if you weren't Jewish, Slav (Slavs being the next set of barely human ranking on Hitler's list), Black or Roma or mentally handicapped.
b) in contrast, communism's universalism attracted (and attracts) people of all ethnic groups, yet at the same time, its very inherent contradictions allowed the leadership to enact "class cleansing" ( class warfare, to eliminate enemies of the people in traditional communist terminology) whenever the need arose, which is and was fairly frequent.
It is a bizarre, cruel twist of fate, for example, that German communists were more likely to survive WW2 in Nazi prison camps than they were in Soviet ones. (Stalin had all murdered, I believe in a steelworks.)
This is precisely the problem when Marxism took over, anywhere. As someone else noted, for the Marxist, the end justifies the means. So any form of violence that can be used to rid the world of the enemies of the people (capitalists and kulaks etc on the way to taking power) is ok. It is valid. It is just.
This means that the most violent, ruthless leader gets to the top - by definition - and when he (or she) is at the top, and has won the battle to take power, then anyone who criticises him (either in reality or in the leader's imagination), then that person can and will be denounced as a traitor, a capitalist revisionist or whatever - and eliminated in turn.
This all-enveloping, brutal process happened every time communism took power. And it is still happening today - see testimonies of N Korean refugees who make it to the south. for such people, even China is a breath of fresh political air.
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True communism is paradoxically found mainly in a very few religious communities where all assets are held in common and each contributes as they are able to the community without gaining personally. It tends to work only at a very small scale.
You may want to term such communities as living "true communism" - but in the normal sense of the word, this is not communism at all, and has nothing to do with the thinking promoted by Engels, Marx or Lenin. This was atheistic, and militantly atheistic at that. (all religions were outlawed in the early stages of communist regimes. After the authorities realised they would not go away so easily, they somehow tolerated, but still sought to infiltrate and eliminate any religious belief.)
