A body is in motion when it changes its position at a certain time/duration. 2. Speed is related to how fast a body is moving. 3. Speed means that a body is moving and covering distance at a certain time. 4. Speed is the distance traveled by an object where as, velocity is distance traveled by an object per unit time in a particular direction. 5. Velocity is the rate of change of distance or direction of a body with respect to time.