Yes, there is a difference between caffeinated and decaffeinated coffee. Caffeinated coffee has caffeine in it, while decaffeinated coffee does not. Caffeine is a stimulant that can increase alertness and energy levels. It can also lead to side effects like anxiety, irritability, and restlessness. Decaffeinated coffee has had the caffeine removed from it through a process of either chemical or water extraction. Some of the flavor may be lost during this process, but many people still enjoy the taste of decaf coffee.