These differences can often be clarified by a brief description. So in this case it is a roll pin, and if you look at the end you will see that it is a rolled strip of steel, like a swiss roll, and is of a uniform diameter. You will never see this design in a taper pin. There will inevitably be differences in terminology, hood, bonnet, trunk, boot, tyre, tire. No need for anyone to get excited about them. I often buy Jeep stuff from the states, and its a lot easier if you take the trouble to find the local terms and use them. So for example they call an anti roll bar a sway bar, so I have just ordered some front sway bar bushes, rather than cause confusion.