What's the difference between frequency separation and dodge and burn techniques?

Hi there, I've been struggling with a particular aspect of skin retouching, and I'm hoping to gain some clarity on the matter. The problem I'm encountering is understanding the difference between two common techniques: frequency separation and dodge and burn, when it comes to retouching skin. I'm curious to learn about the nuances and applications of these methods, as well as when to use each one effectively. I'd greatly appreciate your input.