There is... a lot to unpack here.

A preamble: Considering the sheer frequency by which these comparisons show up (Hitler vs. Stalin, Mao, Pol Pot, occasionally Leopold II) I would seriously question the very premise that Stalin is viewed "more positively" than Hitler in any sense that matters. Invocations of Stalin as a symbol of oppressive or evil statesmanship are ubiquitous, positive comparisons virtually absent, in Western society. What Stalin, arguably, does not do is occupy the position as the "Worst Person Ever" in much Western discourse (If we go outside the West, I do not think it is true that Hitler is anything like 'universally despised') . Why and how certain people come to occupy said position is an interesting question in its own right, but if we are to judge by the number of people vehemently insisting that Stalin is as bad as, or worse than, Hitler, versus those who passionately argue for the opposite, Hitler occupying this position should clearly not be taken to necessarily imply a universal moral judgment. I will go over your text and then try to frame the question in a way that makes historiographical sense to me.

Think about it, Stalin was basically the communist version of Hitler and yet he is seen more positively when he killed millions more of his own people?

There is some ambiguity here. What do you mean by the "Communist version of Hitler"? Was Hitler the "Nazi version of Stalin"? Communism and Marxism were and are widespread, diverse and complex ideologies. Marxian thought has given rise to entire modes of inquiry in its own right. Nazism, meanwhile, is largely defined by the actions taken and opinions expressed by Hitler. While Stalin was extremely influential, Maoism, Juche, Vietnamese Communism, Trotskyism, etc, are different enough that Communism is clearly not monolithic in the way Nazism is. This I believe partially answers the implied question of why Nazism is often seen as more intrinsically evil than Communism.

The second part of your statement is ambiguous. It's unclear who Stalin's "own people" are (Georgians? Russians? Any Soviet citizens?) and whether you put particular weight on him killing 'his own people'. Regardless, it's not really a contest - Hitler's actions, in starting a needless war of aggression, ultimately resulted in the deaths of some 70 million people. Even the very highest estimates of Stalin's body count by Conquest et al. do not reach north of 25 million.

So, this clearly isn't just about the body count. It's also about the reasons for the deaths, the social context, and the underlying thought and ideology. I do not want to go into a side-by-side comparison. Instead I think it suffices to say that the most lethal policies enacted in Stalin's USSR - famine-exacerbating policies and labour camps - had ample antecedents both in and outside Russia. In fact, they look a lot like imperialist policies in the British Empire and other colonialist and imperialist nations.

Now I want to expound on what is arguably the most striking feature of Nazi Germany and its atrocities. Nazi Germany was, in every sense of the word, very modern. It exemplified virtues associated with social progress - industrialization, technological advancement, and so on. As opposed to "barbaric" and "uncivilized" countries, it should by the thinking of the time have been a prosperous, enlightened and peaceful state.

And yet the trappings of modernity was precisely what enabled Nazi Germany to cause slaughter, death and destruction on a scale hitherto unseen. The images most strongly tied to the Holocaust in the Western imagination, the death camps, incinieration, gas chambers and trains, emphasize these aspects, the perverse notion of making a genocide "more efficient" by utilizing infrastructure and industry.

It should be noted, of course, that these notions - of progress, Western chauvinism, social improvement, eugenics (!) and modernity - also served as implicit or explicit justification for many of the atrocious conditions resulting from Imperialism and Colonialism. Nazi Germany, I believe, shattered these, and thus served as a mirror for self-reflection, however reluctant other Western powers might have been to admit it.

Ultimately, I do not believe that it is enlightening, in most cases, to make direct comparisons between Soviet and Nazi atrocities. The differences far exceed the similarities.

Sources and further reading:

The Nazi Dictatorship: Problems and Perspectives of Interpretation; Hitler: Hubris; Hitler: Nemesis; Hitler, The Germans, and the Final Solution (Kershaw)

The Origins of the Final Solution (Browning)

Lenin, Stalin and Hitler: The Age of Social Catastrophe (Gellately)

Harvest of Sorrow; The Great Terror (Conquest) [These are quite dated and should be read with some care taken]

Late Victorian Holocausts (Davis)