① Physical simulation is realized by establishing a physical model. A physical simulation system is a geometric simulation or physical simulation of a real system. Geometric similarity refers to the similar relationship between systems of different sizes in the same physical process (such as mechanical motion process or electric power process, etc.). Physical analogy means that two different physical processes (such as mechanical motion and electrical dynamic process) have the same mathematical description, and they can be each other's simulation experimental models. Mathematical simulation is realized by establishing a mathematical model on a computer, and various physical processes are described by simulating the dynamic process of a computer circuit or the digital operation process of a digital computer. Therefore, the physical simulation system is dedicated; And the mathematical simulation system (that is, the simulation computer) is universal.

② Physical simulation requires real-time simulation, and mathematical simulation can be real-time or non-real-time. (including super real-time and sub-real-time)