2013 Prince George £5 silver proof - different dies or die states?

[Lotad]

I have two 2013 Birth of Prince George £5 silver proof coins and I noticed a difference of the horse’s tail between them both. 
 

I wondered if this was evidence of a different dies or different stages of a die, or something else?

The first coin (highlighted with red). The horse’s tail shows less separation of the hair strands at the end, whereas the second coin is more divided to a higher point. 
 

The second pair of photos show some more minor differences, but I only noticed these with the extra magnification. The easiest to spot was difference in George’s foot, the first coin shows quite a chubby foot compared to the second. There was also a difference between the dragon’s wing membrane. The first coin is softer/curvier with a ridge along the edge of membrane. Whereas the second coin has a spikier overall appearance. 

[Rob]

The dies have had the fields polished to differing degrees. The greater the percentage of field visible, the more it has been polished, and the corresponding reduction in peripheral relief detail is clear.

[Lotad]

Thanks for the explanation. 

[Mr T]

Well spotted.