Speed refers to how fast an object is moving and is a scalar quantity. A fast-moving object (airplane) has a high speed while a slow-moving (snail) object has a low speed. An object with no movement at all has a zero speed (building).

Velocity refers to the rate of change of position over time. This is a vector quantity. If a person in motion wants to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. But if a person is moving one step forward and one step back - always returning to the original starting position, the velocity is zero, Since velocity is defined as the rate at which the position changes.