Is There a Real Difference Between Diffraction and Interference in Physics?

[KFC]

I am reading texts on fundamental physics about diffraction and interference. When comes to diffraction, it takes a single slit as example and using Huygen's principle to explain how the wave transmitt and form the pattern. It sounds like that the pattern is due to interference. One textbook even said that "there is no fundamentaldistinction b/w interference and diffraction ..." It is really confues

1) if there is no difference, why using different terms?
2) whem comes to a pinhole, can I say the resulting airy discs are also come from interference?
3) in Bragg diffraction (2D case), it is all about interference b/w reflected waves, why still call it "diffraction"?

 

[mgb_phys]

You could say diffraction is caused by interference.
I would probably be happy dropping the term diffraction completely and just using interference everywhere.

 

[Andy Resnick]

One way to think about diffraction is the resultant interference between different spatial modes of the total field. So conceptually, there is no real distinction.

In practice, "interference" usually refers to how a single mode interferes with itself (Mach-Zender interferometers, Young interferometers, etc), while "diffraction" usually refers to the more general case (e.g. diffraction by an aperture)