There are 3 main types of openers: chain, screw, and belt drive. Each offer different benefits to you.
Belt Drives- these systems use a rubber belt to lower and raise the door. These openers offer the quietest operation. If you have an attached garage, this is the best choice for you.
Screw Drives- this type of system uses a threaded rod mechanism. As the screw rotates, it moves the trolley up and down the tracks. It requires lubrication two times a year in order to keep it functioning well. These are not the best choice for heavy garage doors, because the weight of the door can wear it out.
Chain Drives- a chain is looped around a rail similar to a bike chain. When the chain moves, it causes the trolley to move up and down the track.