More than likely, the fuel
dock is going to have the same stuff as the station up the street except with red dye. With the introduction of ULSD (ultra low sulfur diesel) in 2007, it got a little more complicated. ULSD was required at all shoreside stations because the diesel particulate filters on the engines cannot handle the sulfur but boat engines do not have these filters and only need LSD. For the most part, everything in the US has become ULSD but some fuel
docks may still stock the strong stuff. The issues with ULSD are that it gels a bit earlier(not an issue except for the arctic explorer types of sailors), and it has a little less lubricity.
If you watch the big boats fuel
up, they often have a home heating oil truck come which is essentially the same stuff as #2 except for additives. However, this will change soon due to taxing and environmental regs on the fuel