It's like DRP with a much heavier emphasis on the police (hence the gamemode name). The MRP aspect we are integrating is apparent in how the police operate on the server (i.e. There are different divisions of law enforcement in which you tryout or apply to join. Upon joining them, you are whitelisted for certain jobs as you rank up.) Meanwhile, there are citizen/criminal jobs players can choose to play as. As you can imagine, going down the path of a criminal means you must be more vigilant of the police, who are a much more difficult force to trifle with than the police on DRP. Normal citizen jobs can be taken as well, such as a banker. Money printing and drug making is also present on the server.
TL;DR Police RP offers a more RP-intensive style of gameplay with a much larger emphasis on the police(structured similarly to MRP), so if you're into that type of RP (similar to life servers on Arma), this server provides that.