Compare and contrast an electric discharge with an electric current.

Both electric discharge and electric current are produced by the movement of electric charge.

Electric current is the continuous flow of electric charge. When there is a potential difference applied to a conductor (for example, a wire), there will be a flow of electric charge from the higher potential to the lower potential. In order for the current to be maintained, there has to be electromotive force, usually supplied by a battery, which brings the charges back from the lower potential to the higher potential. Thus, there has to be a closed circuit in order for the electric current to be produced.

Electric discharge also happens when there is a potential difference; for example, between the two plates of a charged capacitor. A capacitor is typically filled with a dielectric material which does not conduct current well. However, if the potential difference is very large, the motion of the charge from the plate with higher potential to the plate with the lower potential becomes possible. A familiar example of it is lightning, which is an electric discharge between a cloud with the charged water droplets and the ground. However, usually there is no closed circuit present to maintain the flow of charge after the discharge.

To summarize, the electric current is the continuous flow of charge, while electric discharge is a one-time movement of the charge.