Recreational diving is diving for the sport of it whereas there are those that work underwater such as underwater welders and salvage divers.
Recreational Dive Professionals are those people who assist recreational divers and act as guides (Divemasters) and the Instructors and Assistant Instructors that teach scuba to recreational divers. MSDT Master Scuba Dive Trainers that teach many of the specialties of recreational diving. Above that there are IDC course directors that mentor Divemasters that want to become Instructors.