Using a tablet and pen will allow much more control and versatility in creating strokes than just using a mouse. However, one can use a mouse with similar stroking to produce the outcome. The difference is that to create different-size strokes with the mouse requires changing the size while with the pen it just requires more or less pressure on the tablet. Also, though the other options do create variations in the strokes and painting with the mouse, with the pen the differences are more pronounced.