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.
Cordless tools/machines are suited to a variety of different situations, as you are not limited to only working in places with power sources nearby.
The time it takes to fully charge the battery.
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 chuck holds the drill bits or other rotary tools and its diameter determines the types of bits and tools that the drill can use. A larger chuck is compatible with a wider range of bits and tools.
A keyless chuck drill enables you to change out drill bits rapidly without having to use any special keys.
A tool/machine with a higher voltage produces more power.
A drill with variable speed allows you to switch between low and high speeds, giving you the possibility to take on a wider range of tasks.
Higher speeds work better for drilling holes in certain types of material, such as steel, aluminium, concrete, etc. The drill speed is measured in rotations per minute (rpm) when the drill has no-load.
The hammering action provides short, rapid hammer thrusts which make drilling faster and easier. The hammering action is measured in blows/beats per minute (bpm) when the drill has no-load.