Lets take a detailed look: USA: ends the war with the M4A3E8 as its newest standard Medium, but this will shortly be phased out in favour of the M48 It also has a new 'heavy', the Pershing, which will become the M48. It has a host of TDs, SPGs and armoured support vehicles. It has a large number of designs for effective Big Tank killers in prototype form, all of which were cancelled as the war ended. It has a good tactical airforce, and also hads some good jet designs entering service. It has fleets of heavy bombers & escort fighters, including the best bomber going (B-29), which is practically un-interceptable by the current VVS. It has a HUGE and very effective navy. USSR: ends the war with the T-34/85 as its newest standard medium. The T-44 is almost around, but will shortly be replaced by the T-55. It has IS-2 and (in 1945) IS-3 heavy tanks, but not many. It has a host of TDs, and SPGs. It has the biggest/best tactical airforce, but no strategic bomber force to speak of and no workable jets (especially not if Britain witholds the Nene engine, which it would if the USSR and USA went to war). It has a teeny navy, but that's fine as it has a teeny coastline. Basically - after Fighting the Germans the Soviet ground forces were rather reduced. Back home the people were starving thanks to good old Uncle Joe. The US still had plenty of resources to throw around, having never fully ramped up to full wartime economy during WW2. Unless the Soviets could pull something spectacular out of the bag on the ground - and fast - the US would likely win. But it would be a damn hard fight.