Self Tapping Machine Screw Phillips Head : Self-tapping screws can tap their own hole as it is driven into material. These tapping screws feature a flat head that has a flat top and a taper. Flat heads are designed to be used in a countersunk hole. Sheet metal screws have sharp threads that cut into a material such as sheet metal, plastic or wood. They also make excellent fasteners for attaching metal hardware to wood.
Decking Screw Square Drive Bugle Head : Deck screws come in a wide variety of lengths and widths, called shanks. A popular head shape is a square because it holds the driver and doesn't strip as easily as Phillips heads. One feature of deck screws that makes them easy to install is the sharpness of their point. The deck screw drives easily into deck boards, and once set, the head lays smoothly against the deck surface.