system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What's the difference between stand-your-ground and self defense?

This came up recently in another thread and I was looking for a good explanation.
gpt
Under traditional self-defense, you can use lethal force to defend youself from death or serious bodily harm *only if* you can't retreat from the situation.  This is known as the "duty to retreat."

There are some instances where there is no duty to retreat. Most commonly, there's no duty to retreat in your home, so you can use lethal force to defend yourself (again, against a threat of death or serious bodily harm) even if you could run out the back door. This is commonly called the "castle doctrine."

Stand your ground laws effectively eliminate the duty to retreat in public places.  

That said, these are all somewhat nuanced concepts, which vary from state to state, and which don't exist in every state.