What is the difference between the CONTACTOR AND Circuit Breaker? what is The most important characteristics for them?

the contactor is only on and off switch but controlled remotly by applied voltage on its coil terminal to change its situation but CB can be manual or motorized and also work as on and off switch but also it feels the short circuit current and the earth leakage current if it is contain it

Contactor is primiarily used to switch on and off the circuit.

Circuit breaker is used to isolate the circuit in case of fault. It can also switch on and off the circuit, but its primary function is fault isolation.

Contactor is a magnetic CB and you can control the circuit with electrical commands to contactor, but CB is a manual switch with ower current protection.

Contactor can be used for limited power supply and Circuit breaker is used for low to high end applications. Also CB is providing safe isolation of the circuit.

The difference is that the first two lines can transfer electricity without overlap between them and the second prevents just one line

Circuit breaker: c'est unrepture au niveau du cable.                     Contactor: est le connecteur (ouvert ou fermer

A circuit breaker is used to limit the current supplied to a circuit, contactor is in a sense a switch.