According to my opinion:
PRP - related to the infrastructure (inculding human resources) and maintenance programes.
oPRP - Implemented to specifically control and monitor the potential biological, chemical and physical hazards (personnel hygiene, sanitation, disinfection).
May I give you some other examples of oPRP's. Say for example you have several metal detection systems or sieving systems in the process, in true HACCP terms only the last one is the CCP ( the last point at which a hazard can be detected) , however the other metal detection or sieving points in the process still need to be monitored and controlled, these are oPRP's.[A friend also explained difference between PRP's and OPRP's as below:
Clear distinction between PRPs and Operational PRPs is:
The PRP's are not selected for the purpose of controlling a specific identified hazard, but for the purpose of maintaining a general hygienic production, processing and handling environment and may still have an effect on the end product safety if not included in the food safety system.
Operational prerequisites are those that are in place to directly manage or control measures that the hazard analysis has identified as necessary to control to acceptable levels and are not otherwise management by the HACCP plan.
I hope this will help you,