Bare boat charter: As the charterer you are considered the owner of the vessel for an agreed upon period of time. You select a crew and have to pay that crew directly as the charterer. You provide all fuel, food and operating costs. You also need to obtain insurance for carrying passengers. You take on all liability. You are not allowed to bring more than 12 passengers on board with you.
Uninspected passenger vessel: You are going on a boat with a licensed captain, but the vessel has never been inspected by the Coat Guard. At least one of the passengers is paying as a "passenger for hire." The boat can likely only carry six people. This is the most common type of charter when going on a fishing charter.
Passenger for hire: You’re paying to be onboard a boat, which makes it so certain laws have to be followed that help protect you.
Inspected passenger vessel: Your captain is manning a boat that is allowed to take on more than six people. The boat has a certificate of inspection that shows when the Coast Guard last looked at the boat. You are a passenger for hire and are not taking on any added liability because you are not in charge of the vessel.
Source: Tampa Bay Times "Murky Waters: Chartering the wrong boat can have tragic consequences" by Sara DiNatale, November 23, 2017