The first is the power portion and the second is the control. Showing flow of power to motor or other device in a factory environment is the primary focus of the power portion.Showing control of that motor is the focus of the control portion. While power flow is important, the focus is to dissect the control portion. Items such as fuses and disconnect devices may appear in both power and control circuits. The use of symbols is important for both power and control. The types of symbols vary and are somewhat arbitrary based on where you are located and, in some cases, the company you work for. This is contrary to the symbols used in the PLC which must be fixed or uniform. The use of symbols is a descriptive description of the device being used.
