Hammer drills are basically the same as a normal drill except for the fact that they are more powerful. This type of drill can drill holes as well as drive screws or bolts into soft materials. They are typically more powerful than a regular drill because they have a mechanism that helps them increase power by rotating forwards and backwards in rapid succession.
Many construction workers use a hammer drill when working on wood structures because it helps them install different parts of the construction much easier than using a regular drill. Hammer drills can also help you when installing bolts into metal and other materials that are hard for a regular drill to penetrate.
If you work with different kinds of metals especially when doing repairs, a hammer drill would be a great addition to your tool box.