A pressure pot is slightly different from the other popular siphon setup. One of the key things to realize is the name of each type to determine what they mean. Just by looking at the names of each type will explain the major differences between them, but this will explain it further.
A pressure pot is exactly what it says. It is a pot or tank that is pressurized. The tank used is a enclosed container that holds the abrasive media with a mixture of compressed air, supplied from the air compressor. Sandblasting abrasive must be first poured into the tank and is then closed off with a sealed cap. This is a more efficient process because all of the air is working on one goal- to flow a pressurized mixture out of one container.
These pressurized blasters are usually more desirable because they use less air and have higher blasting pressures, making them abrade faster and deeper into the item.
Overall, a this setup usually is more expensive and can require more supplies for operating the control of the abrasive flow.