What do interference and diffraction have in common

[annalian]

Homework Statement

What do interference and diffraction have in common? We are learning the sound waves, but I would like to know all the things they have in common.

Homework Equations

x2-x1=λ/2 (contructive)
3. The Attempt at a Solution
The waves have the same frequency, after the process (interference or diffraction) they don't change; The waves keep having the same frequency (the source doesn't change); They have the same speed and length as they had before, because the environment doesn't change.Can you tell me something else they have in common?

 

[DarkMatter5]

In the double slit experiment a single wave can diffract through both slits and interfere with itself.