No they aren't. Normally you have battery cells (think AAs) -> battery pack -> vehicle trunk, and they're skipping the middle step. It's analogous to how planes have a "wing-shaped fuel tank" (where the wings just have a cavity that you pour the fuel into), instead of storing fuel fluid containers that are separate to the plane.
What OP's link is describing, is where the battery cells literally are the vehicle trunk - as in they're built into the walls, instead of being contained between two walls.