While I would have agreed with this definition of the 2 types previously. Looking them up recently...They are both spring pins because they are larger than the hole the go in and compress/spring to fit and hold. They are also both roll pins 'cause they are rolled steel. To clearly differentiate, I see most manufacturers use terms spiral/coiled or split/slotted. A good spiral is supposed to handle movement and vibration better than a slotted one. But it varies a lot depending on the steel they are made from. The coiled ones tend to be harder steel (more of a true 'spring' steel). I have bent slotted ones but never a coiled one. On the other had, I have found both types made of such hard steel that the slotted ones cracked in half and the spirals shattered into several pieces lengthwise.