Here's the difference:
* Refraction: This occurs when light passes from one medium to another (like air to water) and changes speed. The change in speed causes the light to bend. This is why a straw in a glass of water appears to be bent at the surface.
* Diffraction: This occurs when light waves spread out as they pass through an opening or around an obstacle. The amount of diffraction depends on the size of the opening or obstacle relative to the wavelength of light. This is why you can see the light from a laser pointer spreading out as it shines through a narrow slit.
So, while both refraction and diffraction involve the bending of light, the reasons for the bending are different.
