Question

differentiate between acceleration and deceleration.

Answer 1

acceleration - if the velocity of an object incerases with time in the direction of the motion of the object,then the acceleration of the body is known as positive acceleration.
deceleration - if the velocity of an object decreases with time ,then the acceleration of the object is known as deceleration.                             

Answer 2

Acceleration= rate of change of velocity is know as accelration

Decelration=Deceleration is the opposite of acceleration.   When you decelerate, your                       velocity decreases over time.