It is not uncommon for the public to confuse the differences between RPLS, RLS and PLS designations. In fact, many land surveyors can get confused when licensed in more than one state.
Post-nominal letters and Professional Land Surveyors
The letters PLS (professional land surveyor), PS (professional surveyor), LS (land surveyor), RLS (registered land surveyor), RPLS (Registered Professional Land Surveyor), or PSM (professional surveyor and mapper) follow their names, depending upon their jurisdiction of registration.
Post-nominal letters such as RPLS, today are also called post-nominal initials, post-nominal titles or designatory letters, are letters placed after a person's name to indicate that the individual holds a position, academic degree, accreditation, office, military decoration, or honour, or is a member of a religious institute or fraternity. An individual may use several different sets of post-nominal letters, but in some contexts it may be customary to limit the number of sets to one or just a few.