Controller vs compensator?
Both these terms: controller(for example PID controller) and compensator(Lead compensator) are often encountered in control systems, but what is the difference between these two?


A controller is a closed-loop to have the difference between the output signal and the reference signal minimum. A compensator is also a closed-loop but it changes the shape of the controller's response to meet some requirements (e.g. transient response, rapid load changes, etc.).

Think of them as teachers: One (controller) is the teacher in your school yet the other (compensator) is a private teacher. Your expectation from your school teacher is nearly constant, so you may not give enough attention to him/her. As for the private teacher, you pay him/her to improve your scores and studies.