How does a pepo’s hard rind differ from the outer layer of an ordinary berry?

A pepo is a specialized type of berry that characterizes the gourd family (Cucurbitaceae), such as pumpkins, cucumbers, and melons.12

The primary difference between a pepo and an ordinary berry lies in the texture of the exocarp, or the outer layer of the fruit wall. While a typical berry is fleshy throughout and possesses a soft, thin exocarp—as seen in a tomato—a pepo is distinguished by a significantly harder, tougher exocarp that forms a rind.23

In botanical terms, both are simple fleshy fruits derived from a single ovary, but the development of this hardened outer layer is the defining structural characteristic of the pepo.13