Berdan primers work the same as Boxer primers, but the physical structure is a bit different.
Boxer primers have one central flash hole from the primer pocket into the case, and the anvil of the primer is assembled in the primer, allowing a flat bottomed primer pocket. Looking into the case from the case mouth, one sees one relatively large flash hole.
Boxer primers have the anvil as a part of the case, in the center of the primer pocket. The primer is composed of just the cup and the percussion sensitive explosive. The flash hole(s) are usually to the sides of the anvil. Berdan brass usually has two small flash holes visible from the case mouth, but sometimes just one central one, and very occasionally three.
CDD