Average speed is the average of all the different speeds you experienced as you travelled from point A to point B. You did not travel at the same speed all the time; your speed coming out of your driveway was not the same as the speed you encountered on the interstate highway. Much the same way we determine your grade average, it is the average of all the different speeds you used as you travelled. Instantaneous speed, however, is like a snapshot in time. It is the absolute speed you were travelling at a particular point in time. Think of it, if this has ever happened to you, as the exact moment in time when your car topped the hill and the policemans radar gun took a meaurement of your speed. If it was in excess of the posted speed limit, the blue lights came on and you were detained. So the difference is an average of many speeds compared to a singular, spot-specific speed.
average speed is the speed of a body for a particular span of time.
Like the speed of the car was 80mi/hr. This 80mi/hr represent the average speed of the car.
But instantaneous speed is the speed of a body at a particular time.
the speed of the car at 04:30:25 hr was 80mi/hr. It show that at 4:30:25 the spped of the car is 80 mi/hr. so instateneous speeed represent the speed of the car at a particula point of time