Given:

A body is projected from a height vertically upwards while another body is dropped with the same height.

To find:

Acceleration of 1st body w.r.t the other.

Calculation:

Acceleration experienced by the 1st body:

Acceleration experienced by the 2nd body:

Relative acceleration of 1st body w.r.t to 2nd body:

So, the acceleration of the 1st body relative to 2nd body is 0 m/s² (zero).