World War II was the beginning of tactically and technological advancements, every allied nation dumping millions of dollars in development. New means of weapons set to protect and to destroy. Advanced ways of getting said weapons to the troops overseas. Far more advanced computer technology that was soon introduced into the battlefield created a new era of war. All put forth into providing the Allied forces with substantial amount of supplies to win the war.
To fight a war countries need supplies ammunition and munitions, to blow each other's skulls apart, tanks to do just that, and thousands of small sized condoms to dump over the skies of the enemy. Why? To prevent the spread of STD's of course. Every country on the brink of war can quickly turn the whole labor force into a military production line; about as quick as the 1920's American stock market can crash. .
All the cooperation's within America, whether it was a car factory, tire factory, or just a steel company were basically forced to build parts or even whole tanks, planes, and boats. Just like a car factory there were different models and accessories. Not like options of leather interior or Air conditioning, but maybe a couple 70 mm guns attached to a plain, or a 105 mm cannon on a tank were all part of certain models. For Example the Sherman Tank was small compared to the German Tiger Tank. But there were few advantaged between them. The Tiger Tanks turret was hand cranked while the Sherman's were all motor powered. Giving them an advantage to site up a target more easily than the Tiger Tank, the Sherman's main cannon was in no way a match to the Tiger Tank, but being that they were much more agile they were able to drive circles around the massive Tiger Tanks while putting a few rounds in it with its 75 mm Cannon. .
American's were not so gifted in the sense that military development, the beginning of war, the time that a platoon would run out of ammunition, tanks, or food, and the time they received the supplied was close to unsupportive.