What is the difference between load displacement and light displacement called?

The difference between load displacement and light displacement is known as deadweight tonnage. Deadweight tonnage represents the total weight a ship can safely carry when loaded, which includes cargo, fuel, crew, and provisions, minus the weight of the ship itself when it is empty (light displacement). Essentially, it indicates how much weight a vessel can carry in addition to its own structure when it is fully loaded.

Lightship tonnage refers to the weight of the ship when it is not carrying any cargo or fuel, while gross tonnage is a measure of the overall internal volume of a ship, including all enclosed spaces, and net tonnage is a measure of the volume of cargo-carrying spaces in the ship. Thus, deadweight tonnage specifically focuses on the carrying capacity of the ship, making it the correct answer in distinguishing between load and light displacement.