I can tell you that the NAUI Master Scuba diver training is not based on specialties. I cannot speak about PADI. The course involves course work of about 275 pages with 20 hours of academic work and a minimum of 8 open water dives. From what i gathered in it basically it is more adanced diving without the requirement of getting liablity insurance. Some of the topics covered are
1- Diving equipment- in depth
2- The Diving envoirment
3- Diving Physics
4- Diving Physiology
5- Decompression and Recompression
6- Rescue and Emergency procedures
7- Naviagation for Divers
8-Limited Visiblity and Night Diving
9- Search and Light Salvage
10- Diving Techniques and Deeper Diving
11- Techinical Diving
12- Boating, Diving and Seamanship
Pre-Reqs are
Be 15years old
Have Advanced Scuba Diver
1- Diving equipment- in depth
2- The Diving envoirment
3- Diving Physics
4- Diving Physiology
5- Decompression and Recompression
6- Rescue and Emergency procedures
7- Naviagation for Divers
8-Limited Visiblity and Night Diving
9- Search and Light Salvage
10- Diving Techniques and Deeper Diving
11- Techinical Diving
12- Boating, Diving and Seamanship
Pre-Reqs are
Be 15years old
Have Advanced Scuba Diver