The full form of CISC is Complex Instruction Set Computer, while the full form of RISC is Reduced Instruction Set Computer. These two contrasting microprocessor design philosophies dictate how central processing units execute software instructions. CISC architectures utilize a large, versatile collection of complex instructions where single commands can execute multi-step memory operations. Conversely, RISC architectures employ a smaller, highly optimized set of simple instructions designed to execute rapidly within a single clock cycle, maximizing pipeline efficiency and minimizing power consumption in modern processors.