Hi Maryam,
When you say "difference", what exactly do you mean?
A pipe diffuser can comprise a simple pipe with occasional holes, or a pipe fitted with a diffuser, or a "pipe shaped diffuser unit, etc.
A disc diffuser will obviously be shaped like a disc with a diffuser membrane, or made from a metal or ceramic material.
Maybe if you could clarify what information you are trying to get, then you may get a more informative response.

Aaah, the difference in performance..... well that is a question.
The difference will depend on so many things, primarily the air flow through the diffuser, then the bubble size achieve, and finally the surface area of the diffuser. If other aspects of the the vessel in which the diffusers will operate then the air flow and bubble size will be the main features that will dictate performance.

I would expect that if these parameters are standardised the performances are likely to be similar.