Light direction of image in 3ds max

[nilariver@gmail.com]

Can any body tell how the light direction effect the quality of image? How do we make judgment of this. One of my friend looking to image he will get best out put of the image crisp and clear see the image attched. Can any body tell the logic behind this ? The image which i rendered attaching with this( the completed image with land scape) The friend's image is only building image attached with this. I checked the max file of him nothing special is in rendering settings. The question is how do control the position of light looking the image to get world class rendering output. Please make comment on this