Yes, there are differences between those things.
Poaching is cooking in hot liquid, but the liquid is not boiling or even simmering, so it is a lower temp than both.
Saute generally means you're using a small amount of oil/fat and stirring/tossing the food to spread the oil/fat around on everything while cooking everything. Pan frying generally means you're cooking a larger piece of something and not tossing it around.
Your Firefox should be doing this automatically when it detects the system needs more memory. You shouldn't need to do it manually in almost any case