Write the difference between periodic motion and simple harmonic motion.

(N/A) $1$. Periodic motion is any motion that repeats itself at regular intervals of time. Simple Harmonic Motion $(SHM)$ is a specific type of periodic motion.
$2$. In periodic motion,the restoring force is not necessarily proportional to the displacement. In $SHM$,the restoring force is always directly proportional to the displacement and directed towards the mean position,given by $F = -kx$.
$3$. Periodic motion does not require a specific force law,whereas $SHM$ requires a linear restoring force.
$4$. All $SHM$ is periodic,but not all periodic motion is $SHM$ (e.g.,uniform circular motion is periodic but not $SHM$).