The difference between BRNAV and RNP5 ... BRNAV is the European name for RNAV5, they are identical specifications and the names are totally interchangeable. RNP5 does not exist in ICAO PBN.
The difference between PRNAV and RNP1 ... PRNAV is a European interpretation of RNAV1, the principal differences revolve around acceptable nav sensors and the required functionality. RNP1 is a different kettle of fish altogether, not implemented in Europe.
The confusion between RNAV and RNP specifications arises in part because most multi-sensor area navigation systems (most Flight Management Systems) are RNP-capable, so the terminology employed in their use is that relating to RNP, and practically all FMS will navigate to RNP standards of accuracy even when conducting RNAV operations.