A circular loop has both entrance and exit in the centre of the element; a clothoid loop starts the element at one side, and finishes it at the other side.
The first vertical loop on Copperhead Strike is a very near Circular loop, the entrance and exit to the element are very closely aligned. The second vertical loop is much more clothoid shape, the entrance and exit are quite far away from each other. The second loop however is designed for weightlessness, or possibly even a bit of hangtime at the top. This is why it appears more circular to the average loop that is designed to keep you in the seat through the entire element.