Acharya Prashant explains the fundamental difference between a person and an individual, using the concept of the witness or 'Sakshi'. He describes a person as someone who lacks internal resistance and is entirely dependent on external circumstances for their mental state. Such a person is compared to a fallen leaf at the mercy of the wind, where their internal climate changes according to the random and chaotic nature of the world. This state of being is characterized by a lack of autonomy and a constant shifting of masks based on the environment.