This is a revision of the original North American release of Castlevania. The 'Rev A' designation typically refers to a later print run or updated version of the game cartridge with possible minor bug fixes or alterations to the game code.  The core gameplay remains the same as the original US release, focusing on Simon's quest through Dracula's castle.

Castlevania (USA) (Rev A)

Castlevania - Sonia Belmont Edition