A drink box is a small cardboard box which contains a beverage. Drink boxen usually contain juice of different varieties, but have also been known to hold milk as well.
Drink boxen usually have a plastic-wrapped straw glued to the side. This straw would have a pointed tip at the bottom, and a bendy head a the top. At the top of the drink box, there is a small foil circle. The pointed tip of the straw is used to puncture the foil, and insert the straw into the liquid.
To be considered a drink box, the container must actually be a box, characterized by being made out of cardboard, with the ends folded into triangles on the sides at the top and bottom.
Capri Sun is not a drink box. Capri Sun is a drink pouch. (And a damn pain in the ass to open.)