I wonder if the grid on the Spanish map is an angular grid, rather than linear. Have a close look at the scales on the borders.
Actually, the biggest clue will be the shape of the grids; if they're square, then it's likely to be a linear scale. If they're rectangles, taller than they are wide, then it's likely to be angular; longitude circles are always the same size, but latitude circles get smaller as you move away from the equator, so a given EW angular change is a smaller linear change.