hi gargi, bronzer is used to warm up the complexion by very fair skin toned people. it is often  used as a contour to slim down the face and nose. but it is actually different from contour powders. as i mentioned bronzers are used to add color ( sun tan ) by very fair people, contouring powfer are esp. used to sculpt the face.

Here you go: http://www.stylecraze.com/articles/wear-blush-and-bronzer-the-right-way/