A topper comes in any size like 5x6, 6x7, 7x7 up until 12x12. It getsclipped to the top of your head, and the hair blends with your own to give ita natural look, like a crown coverage extension. A full wig covers yourentire head, and your hair gets tucked inside; there is no blending. A 3/4wig is just a really big cap topper, size 9x9 or higher, up until 12x12.