What is the difference between ref and out?

Excuse me, could you please elaborate on the distinction between the keywords "ref" and "out" in the context of programming? I'm particularly interested in understanding how they differ in their functionality and usage scenarios. Are there any specific scenarios where one would be more suitable than the other? Additionally, how do they impact the performance and memory management of a program? I'd appreciate a clear and concise explanation that highlights the key differences between these two terms.