Although they may look similar at first there are differences that make them work properly in their intended materials. Sheet metal screw threads are intended to displace the base metal and form a sort of nut thread relationship into the hole in the base metal. Wood screws have a deeper, sharper thread profile that is intended to cut into the wood fibers. The wood screws thread pitch is slightly larger and has a more pronounced taper on the end. There are also specialized proprietary wood screw threads that are intended for the newer type composite and polymerized wood products.