Force inside a cylinder vessel is just pressure times surface area. If you have the same pressure(soda carbonation) with more surface area, then you are putting less force on the walls. I don't have any specialty in the materials engineering for canning, but i suppose less force on the walls means you could use thinner materials. However, soda can walls are already pretty thin to start with and from what I can find online, the tops are usually 2.5-3 times thicker. So, I could see it potentially cutting some cost from the tops by making them thinner but i doubt they are manufacturing different tops. It's probably just marketing.