What is the difference between HACCP, HARPC, PRP and OPRP?

HARPC was invented in the US as a replacement for HACCP upon the passage of the Food Safety Modernization Act.  The term has been deprecated.  I use "FSMA-compliant food safety system" in my documents now. 

The Wikipedia article on HARPC will get you started on the differences: 

https://en.wikipedia...ntive_controls 

but basically there is a stronger emphasis on Preventive Control(s). 

PRP means Prerequisite Program(s). An example of a PRP is your Integrated Pest Management system. 

This OPRP term is new to me, but the internet says the OPRP stands for Operational Prerequisite Program(s) and that they control a named hazard that would directly affect food safety.  An example might be maintaining cooking temperature above a specified number, in the production process.

Please What is the difference HACCP, HARPC, PRP and OPRP

i suggest you have a look at these Standards - iso22000, iso22004 for the items other than harpc..

There are also literally hundreds of threads explaining/comparing the above within this forum. Try searching for harpc, oprp respectively.