The difference between RAM (Random Access Memory) and ROM (Read-Only Memory) in computer systems lies in their functions and characteristics. RAM is a type of volatile memory used for temporary storage of data and programs currently in use, allowing quick access and manipulation by the CPU. In contrast, ROM is a non-volatile memory that permanently stores firmware and system software, retaining its contents even when the power is off. While RAM facilitates the performance and speed of active processes, ROM provides essential instructions for system boot-up and hardware initialization.