The postage party cuts out a solid panel where you can blend the stencils onto. The panel die cuts out a frame if you want to add color to the frame. The postage panel die cuts out the windows inside the panels making a frame. You can blend the postage stencils using both but the panel die that cuts out the frame was intended to be more supplemental. The postage party die is the base die that you want if don’t have either one but you can still blend into the cutout panels or negative prices of the postage panel die (but it add an extra step- and if you don't have it adhered down to your work surface, the cutout could shift). I hope that makes sense. Both dies have the same outer dimensions as well. We recommend purchasing the Postage Party die as your base die and the Panel die as a supplemental product.