I noticed what appears to be a discrepancy, and I would like to confirm.
When skillet manufacturers assign labels to their wares (cast iron, triply, etc), then a "12″ skillet" has a bottom diameter actually of just 10″. If/when covered, then the cover diameter is 12″, and that is why it is termed a "12″ pan".
Baking pan manufacturers measure instead the bottom of the pan. Hence an "8″ square pan" has 8″ bottom dimension. On the odd chance it conveniently comes with a cover, then the cover will have a side dimension of 9 1/2″ (or thereabout).
Did I get that right? This is not terribly important for stovetop pans, but it does matter for baking since the dough ends up with a different thickness when poured (which would require adjusting the baking time).