Cargo vans organize enclosed space around goods and working equipment. Passenger vans organize it around designated seats, restraints, and access for people. Similar exterior bodies can therefore contain very different interiors, and neither the model badge nor the size of the empty floor explains the complete configuration.
The difference becomes practical at the doors, attachment points, and loaded cabin. A cargo layout should let the intended goods enter, remain controlled in transit, and leave in a useful sequence. A passenger layout must accommodate occupants and their belongings in the intended seating arrangement. Some vehicles support mixed uses, but those arrangements require their own specifications.