They're the same thing. So the story right now is that the ship's master(captain) informed authorites a bomb was onboard and is now refusing to allow the ship to be searched.
Ya USED to have to score high on a TEST to be certified, but this guy is crazy, stupid or both.
The captain probably got frustrated with security and made some joking comment about a bomb, and then when he realized that this would trigger an automatic (heavy) response, tried to back down and get them to leave him alone. Either way, he's got lots of 'splainin to do.
Actually, the term "master" could legitimately refer to the individual in charge of navigation, at least under British naval nomenclature. The master was/is a warrant officer serving the captain. At least that's what I read a while back when looking at various historical ranking structures.