Velocity
Speed defines how fast something is moving, calculated from the distance travelled over a given period of time. Velocity is the speed of an object in a particular direction.

Vibration
Vibration is simply the oscillating motion of an object about a reference position. A pendulum set swinging to and fro or perhaps striking a thin ruler overhanging a desk, or rapping a bell, Figure 2-1, are all every day examples of vibration. The motion they generate is termed simple harmonic motion.