Commercial crabbing differs from recreational crabbing in several ways, among them the type of equipment. The commercial crabber also needs different types of licenses.
License categories for commercial crabbing in Maryland; LIMITED CRAB CATCHER (LCC), CRAB HARVESTER-300 POTS (CB3), SINGLE ADDITIONAL POT AUTHORIZATION-UP TO 600 POTS (CB6), DOUBLE ADDITIONAL POT AUTHORIZATION-UP TO 900 POTS (CB9) and the TIDAL FISH LICENSE (TFL), which is a consolidated license for the harvest of finfish and shellfish, including blue crabs with trotlines. Both CB3 and TFL licensees may purchase additional allocations. If you are thinking of applying for a commercial license check the Maryland DNR web site for complete instructions. It is not as easy as walking in for a fishing license.

Commercial crab pots are different from those used by the recreational crabber. They are larger, heavier and require a motor operated system to haul them aboard. Electric pot pullers can be obtained in 100, 200 or 300 pound pull in different diameters. The number of traps they put into the water far exceed what a recreational crabber will use. A commercial crab trap is fitted with cull rings, an opening allowing small undersized crabs to escape. They also have an 'umbrella' which allows crabs entering the trap to move into the top portion of trap called the parlor. Once here crabs usually do not find their way back out of the trap. Commercial crab pots may not last for more than a year or two and then must be replaced. Many traps are lost during the season because thoughtless boaters try to run through the trap floats; get a line tangled around their prop and simply cut it leaving the trap on the bottom but no marker on the surface telling where it was located.
The life of a commercial crabber resembles the recreational crabber only in that both rely on the unknown factor of how many crabs will be available on any given day. Many commercial crabbers begin searching for oysters or start commercial fishing once crabbing season has ended.