What is the difference between a frost-free refrigerator and a manual defrost refrigerator?

A frost-free refrigerator uses an automated heating element and fan system to melt away any frost or ice buildup inside the unit, meaning you never have to turn it off to clean out ice. A manual defrost refrigerator requires you to periodically turn off the appliance, empty it out, and let the accumulated ice melt on its own to maintain cooling efficiency.