A magnetic field applies a force to a charged particle due to the particle's movement while an electric field applies a force that does not concern the particle's movement.
Electric field = Newtons/Coulombs
Magnetic field = Newtons/(Coulombs * m/s)
Basically if a charge experiences a force due to its motion, it is from a magnetic field. If a charge experiences a force not due to its motion, it is from an electric field.