Solution

The material used for making a permanent magnet should possess high value of coercivity (intensity of the applied magnetic field required to reduce the magnetization of that material to zero after the magnetization of the sample has been driven to saturation) and also a resonable value of the retentivity ( capacity to remain magnetized after the external magnetizing field has ceased to exist).
On the other hand the materials suitable for making electromagnets should have-high retentivity and low coercivity .