So while an object might reflect the same wavelengths of light continually, and so is in fact a particular color theoretically, our varied perception means that we might see it differently. Our perception of it is also altered by background, illumination, reflected light from other objects, and so on.
For example, a grey ball against a black background will look lighter than when placed against a white background. A large area of yellow tends to fatigue the eye, so it will look duller than smaller, varied areas of yellow.
The main colored mediums for drawing are pencil, pastel and marker. Pastel drawing is sometimes called pastel painting, particularly when used in a way that covers the whole surface. Using a pastel in a more linear and sketch-like way, with much of the paper left bare, is usually referred to as drawing. Although colored pencil is often used in a way that covers the whole surface, the nature of pencil application means that it is almost always described as a drawing medium.
