Seems to me there's a lot of confusion as to what they mean, so here's a short primer.
The general common-law rule of deadly force in self defence is that it is justified if the person reasonably believes that he is in danger of imminent death or serious bodily harm.
Several states codified changes to that standard to add "and no safe retreat is available." This is sometimes called "the duty to retreat."
Stand your ground laws generally simply clarify that in those states there is no duty to retreat. If you are committing no crime yourself and are placed in a situation where you reasonably believe that you are in danger of imminent death or serious bodily harm, you may employ deadly force in your defence (or in defence of a third person).
That's really about all there is to it.
The general common-law rule of deadly force in self defence is that it is justified if the person reasonably believes that he is in danger of imminent death or serious bodily harm.
Several states codified changes to that standard to add "and no safe retreat is available." This is sometimes called "the duty to retreat."
Stand your ground laws generally simply clarify that in those states there is no duty to retreat. If you are committing no crime yourself and are placed in a situation where you reasonably believe that you are in danger of imminent death or serious bodily harm, you may employ deadly force in your defence (or in defence of a third person).
That's really about all there is to it.