Question

what is actually the difference between diffraction and interference eventhough both produce fringes

Answer 1

Light diffraction involves one light source, while interference requires multiple light sources.

Diffraction occurs when light from a single point source passes through a medium with non-homogenous light transmission properties. A really common example is forcing white light to bend around a small obstacle, while simultaneously passing through a thin slit in a wall. This causes the different color wavelengths of light to bend in different directions, which in turn leads to a spectrum of light that we can see.

Interference occurs when the light waves from two (or more) point sources collide with each other. The traveling waves then superpose, so that in some places they add to each other, in some places they cancel out, and everywhere else they are in between. Look up the Two-Slit experiment for a nice example.

Answer 2

Diffraction is the spreading of waves that pass through a narrow opening or move past an obstacle ,whereas, interference is the phenomenon of redistribution of light in a medium as a result of light

Answer 3

Late reply -- but there's no significant physical difference between them. It's the same mechanism, so it's just a question of semantics for the most part, and I wouldn't look twice at somebody who used them interchangeably. Of course, if you're in a course and given a definition to memorize, you should do that...