Quite a few differences there. The rims on the right look thicker. The beads on the right look smaller, but that might be an optical illusion. The left hand side of the 1 is in better agreement on the two reverses in relation to the border bead and central vertical of the portcullis than the right hand side of the 1 which appears to be aligned with the right hand side of the central portcullis vertical on the second coin, but nearly in the middle of the gap on the first coin. The position of the border beads to the design detail is different.
Is there a difference in the number of beads? If you drop a vertical from the outside of the terminal ring, the relative position and possibly number count vary by a midge's.
Is the right hand side a filled die given the somewhat uneven surfaces?