1. Chain Drive - first introduced in the 1920s, it's the most economical; probably the noisiest system. Old designs featured a looped chain that rattled around an open rail to lift and lower the door. Genie has a new design, which features an enclosed in-line chain that pushes and pulls the door for quieter operation than the open rail design.
2. Screw Drive - introduced in 1958, it features a direct-drive motor design for maximum lifting force, and the fewest moving parts of any GDO design. Quieter than a chain drive, it's the strongest and most durable of the three GDO designs. The screw element is available as a single piece of steel (in the professional model) or a three-piece assembly for retail customers (the 3-piece is cheaper, but more moving parts means more parts to fail or wear out).
3. Belt Drive - features a metal-reinforced rubber belt and a DC motor that combine for the quietest GDO available. This might be a major concern in a garage with living quarters above or adjacent. Belt drives are the most expensive type of GDO available.
Genie offers a new GDO that features a screw drive (for durability and strength) along with a DC motor (for silent & efficient operation that matches the belt drives). This new model has a high speed feature that lifts a door twice as fast as a standard door (14" per second as opposed to 7" per second). The door still closes at the standard rate of 7" per second for safety reasons (you don't want to hurt anyone with a fast-closing door). It adds safety in that it opens a door quicker so a driver can get into a garage faster and therefore close the door sooner. It's also got a much bigger and brighter light than other models, so it lights the floor more than the ceiling, unlike some older GDO models.