Top sheets are printed on sheets of paper referred to as "board." The most popular board is between 10 thousandths to 24 thousandths of an inch thick. The board stock is coated on one side, which is applied at the paper mill. Board stock coating is not as glossy as the label stock.
The final manufacturing step on board stock is quite different than on label stock. On the board product, the box maker actually uses the printed board as a structural piece of the finished box. This allows the box maker to finish the box by mounting the printed board as the final step prior to die cutting and folding the box to its final size.
This process is referred to in the trade as "laminating to a single face." Single face means that the container (box) is initially made with only the single face "inside" and the "corrugated" middle section. Then, the pre-printed board is mechanically applied as the "outside" of the box. The manufacturing step that glues the label onto the box is eliminated.