No difference between warfare and genocide
Lucy Dawidowicz called the Holocaust (1986) The War against the Jews. Hitler conceived of war against the Soviet Union as a "war of extermination, the purpose of which was to destroy "Jewish-Bolshevism."

The photos below are of Soviet Prisoners of war. They could have been photos of Jews rounded up from Hungary. 

For Hitler, there was no difference between the Holocaust and the Second World War. The purpose of each was to eliminate Jews from the face of the earth. 

World War II: Soviet Prisoners of War, Mauthausen Concentration Camp

In eight months of 1941-42, the invading German armies killed an estimated 3.3 million Soviet prisoners-of-war. This episode, according to Adam Jones, “vies with the genocide in Rwanda as the most concentrated mass-killing in human history.” There is good reason to think, Jones said, that this rate of killing “exceeds even the worst period of the Holocaust against the Jews.” He states that the murder of Soviet prisoners of war is one of the "least known modern genocides."