Chuck size determines how large of a bit a drill can hold. Common chuck sizes are 3/8", which are suitable for everyday tasks, and 1/2" for tougher applications. A drill with a 3/8" chuck will provide tremendous versatility, while a drill with a 1/2" chuck is best used for heavy-duty jobs or drilling larger holes.
Additionally, different jobs call for different drill bits. Using the right bit not only helps ensure the quality of your work, but helps to preserve the life of your drill and drill bits. Adding different bits to your toolbox will make it easy to drill into different types of wood, as well as metal, steel, concrete or cement. In some cases, your drill might be used for buffing or sanding with the right attachment.