Here in Greece the 3600 costs around 180 euros and the 2600 (as well as the x variant) costs 120 euros. Since the build is mainly gonna be about gaming will I see a difference if I go with the 3600?
It varies. You will see a difference in most cases, the 3600 will be better, it's just about whether the difference is worth the increased cost to YOU.
In some games the 3600 can be nearly 20% better, in others less than 1%. But yes the 3600 is better.