Is it possible to set up different design banner for clients from different countries?

Yes, it's possible using the function of geo-targeting. Create two different banners, paste both banner scripts into your website, and include both of the scripts on your website with adjusted geo-targeting. The scripts will automatically work together showing proper banner depending on the user location.

Using different banners and geo-targeting in combination, you could show different design banners for clients from the EU and outside the EU, or even different banners for users from different US states.

Read more about geo-targeting with instructions on how to implement it.