I had never thought to compare the two, but there are similarities. In each case a more powerful group is taking advantage of thier position to take resources from a less powerful group. In both cases, the excuse is that the people are primitive.
I think that both works reflect the destructive nature of war. War is shown to be horrific in both works. The fundamental difference in both is that Cameron's work shows human beings as being to have an active role in the warfighting campaign. Jake has a crisis of conscience and has a choice to be made in which he has to decide where his loyalties lie. At the end of the film, his efforts are validated in his embrace by the Na'vi. This helps to show how righteousness is rewarded and a morally just order is established. This is not the same in Wiesel's work on a couple of levels. The first is the Wiesel himself argues that the idea of a moral order or a just one in the Holocaust is nearly impossible to find. Additionally, I think that Wiesel's depiction of war is one placed on the victims' point of view. Wiesel shows those who suffer as the civilians, the purely innocent. The people in Wiesel's work are not soldiers and they certainly are not those in the position of political power. Rather, they are the disenfranchised who suffer. It is here where Wiesel's depiction of war is more brutal and less redeeming than what is featured in Cameron's. Finally, I think Cameron's film shows an ending to the war, some type of resolution. In the ending to Wiesel's work, when Eliezer is unable to recognize the reflection in the mirror, the horrors of war are shown to be internalized where the dead's fate is a bit better than the survivors', who are shown to not recognize who they are.