A metaphor is a figurative language device that represents one thing as if it were another, or compares two things not normally viewed as similar, such as time is a thief. This comparison draws attention to the way time is quick and stealthy. Simile
Velocity is the rate of motion, speed or action. An example of velocity is a car driving at 75 miles per hour. velocity. pl. velocity. pl. Rapidity or speed of motion; swiftness. Physics A vector quantity whose magnitude is a body's speed and whose direction is the body's direction of motion.
Speed is the rate of motion, or the rate of change of position. It is expressed as distance moved (d) per unit of time(t). Speed is a scalar quantity with dimensions distance/time. Speed is measured in the same physical units of measurement as velocity, but does not contain an element of direction. Speed is thus the magnitude component of velocity.