What is the difference between S.H.M and oscillatory motion ?

Hint: It is known that simple harmonic motion (SHM) is a type of oscillatory motion which is defined for the particle moving along the straight line with an acceleration which is moving towards a fixed point on the line such that the magnitude is proportional to the distance from the fixed point.

Complete answer:
We know that the oscillatory motion of an object is defined as, a motion repeating itself is referred to as periodic or oscillatory motion. An object in such motion oscillates about an equilibrium position due to a restoring force or torque.

But the simple harmonic motion can be defined as, a type of oscillatory motion which is defined for the particle moving along the straight line with an acceleration which is moving towards a fixed point on the line such that the magnitude is proportional to the distance from the fixed point.

So, the differences between simple harmonic motion and oscillatory motion are:
- Oscillatory motion is the general term for periodic motion but Simple harmonic motion is the simplest type of periodic motion.
- The restoring force acting on the particle for oscillatory motion is not specified but in simple harmonic motion it is directly proportional to the displacement of the object and acts in the opposite direction.

Note: The restoring force in oscillatory motion can be of any kind and related to the displacement of the particle with any power of it, in simple harmonic motion the force is always related to the first power of the displacement.