Hello Earl, just saw the post here and thought I would add to Joe’s post for you.
Rheostats and a potentiometer are very similar devices, they are both forms of a variable resistor. Rheostats are generally wire wound for higher wattage ratings than pots are. A big pot is 2 watts, but a big rheostat is 200 watts. Potentiometers come in very small sizes too, sometimes call “Trim Pots”. Both pots and rheostats are usually 3 terminal devices with, and the center terminal is usually the wiper, the 2 outside terminals are each end of the resistor itself.
Hope this helps you, and like Joe said, check out the Videos “What is a potentiometer?” and “What is a Rheostat?”