What is the DIFFERENCE?
The on camera flash
Many of the DSLR cameras have what is called a pop-up or on camera flash, but if you have used this feature you will know that it doesnt always help, well sometimes it even makes your image lighting worse. Why is that? Well it is because the light, or flash is on the camera and way to close to the lens, and this can create the most unflattering harsh light on your subject.
The reason the light from the pop up flash is a very small light source, and the smaller the light source the harsher the light it produces and sends out.