Rheostat vs. Dimmer: What's the Difference?
Main DifferenceThe main difference between Rheostat and Dimmer is that the Rheostat is a a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider and Dimmer is a a device used to lower the brightness of a light.
Rheostat
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.