nail
finishing nails and box nails are made of the same diameter wire. The head of a finishing nail is only slightly larger in diameter than the body of the nail so that it can be embedded (set) into the surface of the wood.
There is a slight depression on the top of the head to prevent the nail set from slipping off the head. The small hole that is made in the wood is filled with putty or some other type of filler to hide the nail when the surface is finished.