A brushed motor is the one with a regular electric motor. Brushes are present in such motors and, you will notice that these brushes wear down over time and need to be replaced.
A brushless motor, on the other hand, does not contain brushes and saves you from such trouble. It has been observed that brushless cordless drills come with a heavier price than brushed cordless drills. Nevertheless, brushless cordless drills are preferred over brushed cordless drills.