Self drilling screws also know as TEK screws, these screws work as both a drill bit and a fastener. TEK screws do not need a pilot hole because of the drill bit end.
They work perfectly well at fastening thin pieces of metal together. Commonly used when doing frame work on cars, or attaching sheet metal to a metal frame. TEK screws have much variance in types and uses than tapping screws.
Self tapping screws tap their own head, so they need a pilot hole slightly smaller than the screws diameter. Tapping screws drill a pilot hole into wood or another soft material. Self-tapping screws are ideal for all sorts of materials such as wood, metal and brick.Not all tapping screws have a pointy tip, some will be blunt, notches on the thread for thread-cutting or flat.