Oscillatory motion simply means the motion repeats itself over time, moving back and forth about an equilibrium point.

Simple harmonic motion (SHM) is a specific type of oscillatory motion with these key characteristics:

* Linear restoring force: The force acting on the object is directly proportional to the displacement from equilibrium and always acts in the direction opposite to the displacement.

* Sinusoidal displacement: The object's displacement, velocity, and acceleration all vary sinusoidally with time.

Therefore, any oscillatory motion that doesn't fulfill these two conditions is not SHM. Here are some examples:

* Damped oscillations: These oscillations gradually decrease in amplitude due to friction or other dissipative forces. They still oscillate but don't have a perfectly sinusoidal displacement.

* Forced oscillations: These oscillations are driven by an external force. The frequency of the oscillation can be different from the natural frequency of the system, resulting in non-sinusoidal motion.

* Anharmonic oscillations: These oscillations have a restoring force that's not directly proportional to displacement. This results in non-sinusoidal displacement and can lead to more complex patterns.

In short, while all simple harmonic motions are oscillatory, not all oscillatory motions are simple harmonic.