Question

give two difference between acceleration and retardation

Answer 1

acceleration means increase in the rate of velocity with time.
retardation is the decrease in the rate of velocity with time
acceleration is positive
retardation is negative

Answer 2

Acceleration is the change in velocity of a body with respect to the time.
It is positive that is in the direction of motion

And when the acceleration is negative that is in opposite directions to motion it is called retardation or deceleration
It is always negative