hammer drill is used to drill through mansonary materials, a compact drill normally does not have "hammering" action when drilling. Compact drill, or namely normal drill is for drilling through wood, metal etc, can also be used for driving screws or fasteners. But for driving screws and fasteners, an impact driver is far superior. Also to note, normally, a hammer drill can be used as a reguar drill, but hammer drills are usually heavier and bulkier. They can be used as a regular drill but not necessarily feasible.