Rigid must re-doing their website again as they used to have the beam patterns up for all their lights. I checked the Marine pattern and it is similar to the regular D2 dually pattern and that is going from memory of course becuase currently thier website does not have the beam pattern associated with the D2. From what I read the difference isn't in the beam pattern, its in the housing and components of the units as they need to be able to handle the marine environment.
Thing that got me pondering is that the marine grade light is 20 bucks cheaper than the regular light. Normally anything that has marine grade components comes at a higher price.