Commercial diving varies from recreational diving by orders of magnitude. Public Safety Diving approaches Commercial diving but is still akin to flying a Cessna v. flying an F-18. The hazards, required training, and rules of the road are very different. To examine these, let us start with OSHA. OSHA sets standards for safety in the workplace. The section of the rule book that defines these rules are to be found in 29 CFR 1910. A few of these will be highlighted, however this is not a complete list of requirements by any means. This overview is meant to illustrate the difference in requirements JUST for safety.
29 CFR 1910.410 defines the training requirements for divers. Part of this sections says that although there is no national certification or licensing of divers, they must be trained for the type of diving they are involved in (ie., surface-supplied air or mixed gas use). OSHA will accept a commercial diving school's commercial diver certification card as proof of training.
29 CFR 1910.430 defines the equipment required for use by commercial dive teams. If you have anything coming in from overhead, plan on wearing a helmet. Some operations require surface-supplied air and communications with the surface.
29 CFR 1910 sub-part T sets the minimum size of the commercial dive team, which is usually a minimum of (3); a Person In Charge, a Line Tender and a Safety diver. Obviously, this is in addition to the diver(s) in the water. Some overlap is acceptable in certain circumstances.
OSHA is not trying to be overbearing and I do not think many of their rules are unnecessary. If you or your employer find them burdensome, perhaps you need to rethink your priorities. No job is worth dying for if you are not in the US Military or a police officer. Even then, it is a terrible tragedy. Follow the rules and stay alive. Please watch this animation of an actual commercial diver death investigated by OSHA. It's no joke.
While Public Safety Diving can have similar hazards, the aim of evidence recovery, body recovery or rescue afford a somewhat different set of safety rules and training. PADI and other dive organizations have Public Safety Diver certifications that should be a must-have for personnel on these types of teams. Organizational training should be somewhat frequent, with additional planning and training specific to particular dives and circumstances.
A recreational SCUBA diver, without the training should attempt neither, at any time! The hazards can quickly overwhelm the untrained, and occasionally, takes the life of even trained divers.
While there is a sense of great satisfaction diving with a purpose, Public Safety Divers and Commercial Divers are trained to manage the hazards associated with their craft. It is truly an exciting and fulfilling experience and one I recommend highly. Test the Waters has created and trains an excellent Public Safety Dive Team and I would recommend you use them for your training and approach them with your Public Safety Diver needs. Join us. You won't be disappointed. For commercial diving, there are a hand-full of commercial dive schools in the US. Do your research and choose wisely. Perhaps go on You-Tube and check out the 'Salty Diver' channel. He is a commercial diver and is both knowledgeable and somewhat critical in his assessment of the commercial diving schools and community. There are also many videos on YouTube from the dive schools (Of course, these are advertisements). All of them accept the GI Bill.
Be safe. AND GET TRAINED!