What is the main difference between squirrel cage & slip ring motor? and why slip ring motors are used for higher loads? & why not squirrelcage motor?

SCIM:

        Rotor end rings are short circuited,

        cylindrical rotor shape,

       tough and rugged,

       less starting torque than WRIM

      less maintenance

       less cost

WRIM:

      high starting torque

     more maintenence,

     rotor coils are end with slip rings

    rotor current control available,

because of high starting torque WRIM is preferred for heave loads

The main difference is the construction of the rotor.

 Slip ring motor can be used for high starting torque applications. Its starting torque can be increased be using rotor resistance. This is not possible in squirrel cage induction motor.