What is the difference between the symbol of physical quantity and that of unit in physics? If the physical symbol and the unit symbol are the same, for example, the physical symbol is w, and the unit symbol is w, how to distinguish them?

What is the difference between the symbol of physical quantity and that of unit in physics? If the physical symbol and the unit symbol are the same, for example, the physical symbol is w, and the unit symbol is w, how to distinguish them?

In physics, all physical quantities are represented by symbols, and their units are also represented by symbols. The symbols of physical quantities are in upper case and lower case. For example, the symbol of power is in upper case P, and the symbol of mass is in lower case M. the symbols of units of physical quantities are in upper case and lower case. For example, the unit of current is ampere, which is in lower case M