HSS is a standard drill bit metal type. Typically it has a 118-degree drill point angle. It is used for drilling into soft or mild metals such as cold rolled steel, aluminium and wood.
Cobalt drill bits are used for drilling in tough, high-tensile strength metals like Inconel, titanium and stainless steel. They are made of heat resistant, 3% - 8% cobalt high-speed steel and typically have a thicker web construction which also has a split-point.
Titanium Nitride is a surface treatment. TiN improves the life of a drill bit by reducing wear and increasing heat resistance. TiN drill bits are more efficient due to the low amount of friction and the very high surface hardness.
A typical masonry drill bit has a shank and flute made of mild steel and a very hard carbide insert, which has been brazed onto the tip of the bit. They are used for drilling into concrete, brick and mortar and some types of stonework.