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 defined as the rate of change in distance with respect to time. Velocity is defined as the rate of change in displacement with respect to time. Notice the words distance and displacement are the only difference between the two definitions.