What is the difference between open loop and close loop control?

simply open loop system is a blind system it cant adjust it self to the steady state On the contrary the closed loop system is that smart system who can adjust it self by feed back control :)

The main difference between them is "Feed Back".

Closed loop system monitors the "output" whereas the open loop system does not.

Feed back system is the main difference between the open loop system & close loop system. open loop system will not have the feed back system. Closed loop will have the feedback system.

Closed loop control uses feedback to improve system response whereas open loop control does not have any sort of feedback. With the help of feedback you can monitor your output at any time and compare it to your reference point. This gives you, your error and with the help of a proper controller you can make this error zero and your output will be at your reference point (or track your desired trajectory). Also closed loop control helps the system reject disturbances whereas in open loop you cant reject disturbances and if an open loop system receives any disturbances it will divert from it's path and your output won't reach the desired one.

closed loop system is the system which do check to the output then send the result through the feed back , while open loop system do not check it`s output

For example a movement of a robotic arm using an encoder is a closed loop system. Each time the encoder reads the position and gives a feedback, i.e whether reached desired position or not.

Open loop system is a system without retro-action that does not take feedback into account during regulation.Closed loop system is a system in which the previous state of the output contributes in defining the future state of the same output.

closed loop systems consist of a feedback ....while the open loop doesnt

ooooooooooooooooooooooooooo   feed back   ooooooooooooooooooooooooooo 

closed loop system has a feedback stage, while open loop system works without it.

Open Loop Control has no RESULT FEEDBACK, whatever the output is. But Closed Loop is RESULT ORIENTED Control within a period of time.