Perhaps I can add a little more to the clarification, at least within the PADI (biggest) organization. A divemaster is the first level of professional rating. A divemaster is thereby qualified to lead and work with certified divers. They also, with an additional divemaster credential, can teach snorkeling classes, scuba review for certified divers who haven't dove for a while, and Discover experiences, in a pool or in open water, to a limited number of students. The Discover esperiences are just that- a chance for a person to try scuba and see if they like it. Discover Scuba Diving is sometime called a "resort course, and a dive master with the Discover Scuba Diving leader credential can lead that for a limited number of people at a time. Dive masters lead certified divers on dives, and under the supervision of an instructor, works with certified divers in their continuing education. They assist with all classes, but do not "sign off" on or certify divers at any level. Divemasters also get to do other fun things: fill tanks, load tanks and rental gear on to dive boats, clean dive boats after outings, sweep the floor of the dive shop, take out the trash, set up canopies on the beach for training days, set up and retrieve training platforms- all that good stuff.
DivemasterDennis
DivemasterDennis