Use... I mean just opening and closing. I've not seen one with a leaf spring and not sure how that would work. The button type I've seen works via a button, is merely a release when depressed.
The coil spring by closing the blade adds tension to the spring. Once the blade is released the coil exerts force and opens the blade. The coil spring is coiled and hidden inside the front bolster and one end anchored to the blade. I think Buck has started building some of these. Otherwise the warranty is voided. DM