*grossly oversimplifies the end of WWII*
USA: We can produce whole shiploads of M26s SO let's just drive M4 variants everywhere.
Japan: Increasingly intense strategic bombing means we CAN'T produce this prototype fighter better than the P-51, let's just dig in a batch of tanks which were outgunned in 1938.
USSR: This is basically what the Germans have except it's stamped out of the crappiest steel and also Warsaw Pact forces will still be using it in 1980
Germany: We'll have resentful, half starved slave labor manufacture an incredibly expensive, hard to repair [Sache] which teenagers will field against Brit/Canadian/Polish vets.