Difference Between Interference and Diffraction

Interference and diffraction are two phenomena of light. Interference is a phenomenon where two light waves interfere with each other. On the other hand, diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle or aperture. 

For interference, two coherent sources are must needed. But diffraction occurs from one light source. Here we are going to tabulate some key differences between interference and diffraction.

Sl No.	Interference	Diffraction
1	Interference occurs due to the superposition of two different wavefronts coming from two coherent sources.	Diffraction is due to the superposition of secondary wavelets from the different parts of the same wavefront.
2	Fringe width is generally constant.	Fringes are of varying width.
3	Points of minimum intensity are perfectly dark.	Points of minimum intensity are not entirely dark.
4	All bright brands are of uniform intensity.	All bright brands are not of the same intensity.
5	Two coherent sources are needed in interference.	Only one source is needed in diffraction.

These are some major differences between interference and diffraction. Happy learning.