Against the Soviet union they had the initial advantage of modern equipment but couldn't compete with Russian land advantage. If they had had better tactics and had consolidated, then things would have been different. Instead they targeted Moscow during winter -- insanity No, the Wehrmacht was diverted from Moscow by Hitler to take over Kiev first over the objections of the Wehrmacht generals. If the German army hadn't wasted time messing with Kiev, they could have take Moscow before winter.
Another problem with the invasion of the Soviet Union was the delay caused by Hitler rescuing Mussolini from the latter's disastrous moves in Greece, Albania, and Yugoslavia. Had the Nazi invasion started on May 15, 1941, rather than June 22, it is possible that the Wehrmacht could have achieved many of its objectives prior to the onset of the Russian winter. It also would have given German industry additional time to properly equip the military against the harsh conditions.
Churchill reportedly said, when an aide reminded him that Italy would fight on the Axis side during the war, "It's only fair. We had them last time." Combined with Italian disasters in North Africa,a region about which Nazi ideology or German goals had no particular interest, Churchill's sarcasm was prescient.