Plate Type Sprockets are provided as a flat plate with no hub. This enables you to drill & mount the sprocket in your machine without having a hub. These come with no keyway & set screw. Plate type sprockets come in two standards i.e., British (BS) & American (ANSI). They are called A type Sprockets.
Hub Type or Finished-bore Sprockets are provided with standard keyway & two set screws. The keyway is for fixing your sprocket to the shaft to keep the sprocket from spinning. Set screw is for locking the sprocket onto the shaft. These come in two standards i.e., British (BS) & American (ANSI). They are called B type Sprockets for one side hub & C type Sprockets for both side hubs.
