Flat heads are countersunk (cone shaped under the head) with a flat top. Slotted drive has a simple slot for a flat bladed screw driver.
A low carbon steel for general use. Zinc plated for moderate corrosion resistance.
Solid brass. An alloy of primarily copper and zinc with good corrosion resistance. Used mostly in decorative and electrical applications. Exact color varies.
Solid bronze. An alloy of copper with greater strength and corrosion resistance than brass. Exact color varies.
Round heads are domed and look like half of a sphere. Slotted drive has a simple slot for a flat bladed screw driver.
Screws with machine threads for use with a nut or in a tapped hole.
Screws with an Allen wrench drive.