Can you spot the difference?

So what is going on here? 😜
Few weeks ago I bought these from local internet site selling second-hand items, I paid 25€+ shipping for them. Once I recieved them I noticed an interesting thing, something wasent right! I contacted the seller and told him about the problem, seller didn’t notice this issue (people in general wouldn’t notice) and I believed him. The seller refunded the money and I kept the boots.

Can you spot the problem?