Distinguish between uniform and non uniform acceleration.
Acceleration describes the rate of change of both the magnitude and the direction of velocity.
Non-uniform acceleration constitutes the most general description of motion. It refers to variation in the rate of change in velocity. Simply put, it means that acceleration changes during motion. Uniform or constant acceleration occurs in a a type of motion in which the velocity of an object changes by an equal amount in every equal time period. Difference between uniform and non uniform acceleration is that in the first case we have constantly changing velocity and in another case - arbitrary changing velocity, refering both to magnitude and direction of velocity.