A reversible drill can alter its rotations from a clockwise direction to a counter clockwise direction, a feature that makes it suitable for both drilling and driving.
A hammer drill contains a hammer clutch or a hammer-like mechanism which provides a circular rotation and a forward driving force. A hammer drill is capable of performing heavy-duty tasks, but it can also be used as a regular power drill.
The height represents the vertical dimension of the product. We consider a smaller height better because it assures easy maneuverability.
The width represents the horizontal dimension of the product. We consider a smaller width better because it assures easy maneuverability.
A drill with a pistol grip handle is usually compact and lightweight, making the tool suitable for a large variety of apps and easy to use.
We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.