The 14 January printing on the left had Scotland's stamp printed in grid position 8 only. The 31 May printing has the Scotland stamp printed in positions 3, 6 and 7.
We can now show the grid positions for all four stamps, and these show that
England is in positions 1, 2 and 5;
Scotland is in 3, 6 and 7;
Northern Ireland is in 4, and
Wales is in 8.
But there are noticeable differences in the actual stamps as well.
Cartor Security Print have produced the original and the new printings. In all cases the original 14 January printing is on the left, and the 31 May printing is on the right.
Northern Ireland, original is noticeably greener or bluer depending on your eyes/monitor. New print is grey.
The Scotland stamp is probably the least distinguishable but the new one is lighter.
The new print of the England stamp is notably lighter than the original. Over the years there have been many variations in the colour of this design, as different processes and printers are used, but this is the most noticeable variation on the same value.
The question remains, though, how many times do the printers need to be told that a new plate should not have the same number as the one it replaces???
Scotland 2nd class
Examples of a new printing by Cartor of the Scotland 2nd class are also in a distinct shade, with more magenta*. On the left, De La Rue; centre the 1st Cartor printing (24/04/12); right the 2nd Cartor printing (28/06/13). The gird formation on these is the same as before so they may be the same plates, with just a different ink mix.
* 1st class second Cartor printing. This was also reprinted on 28/06/13 (both values are on the same press plate) but no there is no noticeable difference, suggesting that rather than 'more magenta' there is less cyan.