What is the main difference between refraction and diffraction? A Refraction is a phenomenon that affects light; diffraction is a phenomenon that affects sound. B Refraction involves the bending of light; diffraction involves the bending and spreading of light, usually around an obstacle. C Refraction usually happens in the atmosphere; diffraction usually happens closer to the earth's surface. D Refraction involves changes to the density of light; diffraction involves changes to the speed of light.