Difference between Flywheel and Governor

Flywheel	Governor
Flywheel reduces the fluctuation of speed during the thermodynamic cycles, but it does not maintain a constant speed.	Governor is a device to control the speed variation caused by the varying load.
The working of a flywheel does not depend upon the change in load or output required.	Governor operation depends upon the variation of load.
The operation of flywheels is continuous from cycle to cycle.	The operation of a governor is intermittent.
Speed control in a single cycle	Speed control over a period of time
The function of a flywheel is to store energy when mechanical energy is more than required for the operation and release the same when the available energy is less than required. Its inertia helps to run machines at a dead center.	The function of a governor is to regulate the fuel supply according to the load requirement and run the machine at a constant speed irrespective of the output required.
Do not have any control over the supply of charge or fuel.	Control the supply of fuel to the engine
It is relatively heavy and has large inertia force.	It's a light machine part
It is used in engines and fabricating machines such as punching machines, rolling mill, etc.	Governors are provided on engines and turbines.
It is desired where the fluctuation in input torque. e.g.: four stroke engine	Desired where the constant speed required e.g. Generator (there is even electronic governor for diesel generator)