The most common type of cleaner is a suction side device. These auto cleaners are attached to the the suction or vacuum port of your pool. When you turn the pool filter pump, the suction powers the cleaner and they move randomly around the bottom of the pool. Debris such as sand, grass, leaves, etc. are sucked up the cleaner, through your pipes, your pump basket and finally your swimming pool filter. Some cleaners have a filter bag as part of the cleaner, but the majority of economical suction side vacuum cleaners use your pool filtration system.
A Robotic Cleaner is an electric machine. The cleaner has a long power cord and transformer that you plug into a socket. Once you drop the cleaner into the water, the cleaner will work it's way around the pool in a programed way. This type of cleaner is self contained, meaning it has it's own filter bag and does not run off your pool pump.
When choosing your self cleaner, first select your type of pool; either above ground or inground.