What is the difference between flywheel and governor

A flywheel is a big circular mass to store energy when in the form of rotational kinetic energy slowly added to it by intermittent torque, generally in a internal combustion engine Pistons . Once the wheel starts rotating its intertia will keep the Rytham. To give an anology just take a solid disk suspended on its center with frictionless support and attach a crack leaver at the center and try to rotate till it rotates at a constant speed. Then slowly the force on ur hand reduces now after the speed is reached if you try to added more force or reduce the force the wheel will not slow down or speed up quickly this way it will keep th Rytham or speed.