Continuous-feed models, the most popular and the least expensive type, are controlled by a wall switch. Once it's operating, you can feed a continuous stream of waste into the unit through the open drain.
Batch-feed models dispose of waste in batches, usually 1-1/2 to 2 quarts at a time. They operate by replacing the drain lid, which activates the power switch.
Motor sizes vary.
Motor sizes range from 1/3 horsepower to 1 horsepower.
An overload protector shuts off the motor in case of jams.
Some models incorporate antijamming devices such as automatically reversing blades or an antijamming button. Others use a supplied wrench to manually turn the motor shaft and free jams.
Garbage disposals are noisy appliances; evaluate the amount of noise insulation in the models you're considering.
Also consider where you're going to install the disposal unit. For example, if you have a small bowl next to a bigger bowl for your sink choice, not every disposal unit will be able to fit.