Four types of flaps. You will see them on various aircraft. Often Slotted flaps are confused for Fowler type flaps. Split flaps often do move to the rear as deployed, but the length of movement is only sufficient to create a slot. This improves lifts by allow air from under the wing to travel through the slot and over the surface boundry layer on the top of the flap which increase lift dramatically over standard (plain) or split. I addition to flaps, there are a host of high lift devices for the leading edge such as droops, slats, and slotted slats.