What are the fundamental differences between Gaussian units and SI units in the context of electromagnetic theory?

In the context of electromagnetic theory, the fundamental differences between Gaussian units and SI units lie in the way they define the basic electromagnetic quantities such as electric charge, electric field, magnetic field, and current. Gaussian units are based on the electrostatic unit of charge, while SI units are based on the coulomb. This leads to differences in the equations and constants used in electromagnetic theory calculations.