Stress and pressure are both force per unit area. How do you differentiate between them?

Explanation

Stress is the inernal restoring force per unit area set up in a body under the effect of an applied deforming force. Puressure is the external force per unit area.
Stress will come into play when a body undergoes some change in its dimensions under the effect of deforming force. Due to pressure, the body may change its dimensions.