Difference between deceleration and retardation Share with your friends Share 1 Roli Srivastava answered this Deceleration and retardation are the same thing. They both are terms used to define negative acceleration or slowing down of speed. Both words can be used in general context. 0 View Full Answer Aayushee answered this Deceleration and retardation are synonyms for each other. They both mean negative acceleration or slowing down of speed. 2