The scope of Supreme Commander (SC) is similar to that of USE. It covers the same period of the entire second war world but it has a less number of smaller scenarios. It is a point in which USE shines.
Each turn represent one and half months in average, because summer has more turns than winter which I think it is realistic. Most of large operations were carried out with good weather in summer or spring seasons. Each hex also represents 60 miles approximately. Note that each turn in USE represents one month.
The number of players also fluctuate between 2 (Axis) vs. (Allied) to 5, in which two players can control Italy and Germany and the rest of players will control UK, (France and USA) and USSR.