Why the Royal Navy called them accelerators

What was a carrier accelerator, and how did it differ from a catapult?

The Royal Navy used accelerator for carrier launch equipment and catapult for the different systems used on battleships and cruisers; later terminology converged on catapult.

The technical vocabulary reflected differences between the systems and their applications. Later common practice adopted the broader American term, catapult, as equipment and terminology converged. In the interwar Royal Navy, catapult normally described equipment on battleships and cruisers, while accelerator identified carrier launch gear. Keeping the original term helps readers understand contemporary documents without mistaking the distinction for an error.