Answer: please find the answer in the explanation.
Step-by-step explanation:
Harmonic can be experienced by any body that repeats itself. The pattern can be sinusoidal, square, tooth etc.
The fundamental differences between the harmonic oscillator dynamics and the simple pendulum dynamics are:
1.) The harmonic oscillator dynamics can be sinusoidal or square wave so far the motion is periodic while the simple pendulum dynamics is always sinusoidal.
2.) In simple pendulum dynamics, the period of oscillation is independent of the amplitude. While the period in harmonic oscillator dynamics depends on the amplitude.
3.) Differential equation is only one method to analyze the simple pendulum dynamics where there are several methods to analyze the harmonic oscillator dynamics.