ImgBurn can output straight to the burner, so you don’t have to make an image and keep it on the hard drive. You also have control on burning speed, which is often times very important depending on the quality of your blank media.
ImgBurn can also bitset +R disks for many types of burners, increasing compatibility in stand alone players that are picky.
If making dual layer dvd burns, ImgBurn can set the layer break correctly, which not many burning programs do well.
There are probably other advantages I am not aware of, but you can talk to LUK over at the Imgburn forum or here at the cdfreaks ImgBurn subforum if you want more information.