Yes, prisoners were on occassion shot. But that's, not irrelevant more like.. not so relevant. What's relevant is first of all the orders regarding prisoners and even more relevant is how those prisoners were being treated if they, as the vast majority did, survived the initial capture. And that points to a major difference between the sides. Soviet POW's captured by the Germans had a deathrate of around 60% while Allied POW's in the same role were by and large being treated in accordance with The Geneva Convention of 1929. Likewise German POW's captured by the Russians had a fairly high death rate as well, particularly early in the war but not as high as their Soviet counterparts. Whereas German POW's captured by the Allies were also generally treated correctly.