Would the result have been somewhat different if Hitler would not have given an order to attack Russia?

I don’t think the results would have been much different if Hitler had not given an order to attack Russia. It is true that fighting on a second front with Russia in the east made things more difficult and costly for the Germans. However, there were other reasons why Germany lost the war. For example when the German ports were blockaded, the Germans did not handle the supply shortages successfully. Eventually, the German people and soldiers were starving, had little clothing or cleaning supplies and were suffering from all sorts of diseases. Also, Germany’s military equipment was complex and hard to manufacture and maintain.

Hitler made many bad decisions, such as abandoning Field Marshall Rommel in Africa. Hitler also pledged he would never retreat, wasn’t prepared for resistance, and was so cruel his enemies would not stop at anything to destroy him.