Difference between silhouette and contour

(Drawing)In silhouette you only draw the edges, while in a contour drawing you had to draw all visible lines and divisions. 

For example: you are to draw a silhouette and a contour drawing of a person in profile. To draw its silhouette you only have to draw the outer edges, tracing it until you made a whole shape. A very good silhouette is your own shadow, a silhouette of you. 

For the contour drawing not only does you draw the silhouette you had to fill it in too with other details. There should be lines to indicate the hair, the nose, the ear, the eye, the lips, the wrinkles and other such stuff. 

That is the silhouette only concerns on the shape of the outer edge of the figure, while a contour drawing is interested in using lines to interpret the figure.