Quote from GW2 staff in GW2 fb page regarding the difference of EU and NA copies :
-To play from North America you must purchase a North American copy of the game. To play from Europe you must purchase a European copy of the game. Note that this restriction impacts where you can play from, not which game worlds you can choose to play on.

By purchasing the correct copy of the game, you're supporting the game in your country, and you'll be connecting to your local data center, using your local customer support team, and downloading the correct language support for your country.

-And don't worry -- we want you to play with your friends wherever you are. This policy only affects where you can login from -- not which worlds you can access. People from NA will be able to play with people from EU at launch. We've got two datacenters -- one in NA and one in EU. Those who do not fall into either of those two regions will default to the NA datacenter.

Quote from a commenter at GW2 fb page regarding the difference of EU and NA copies :
The copy u get means u need to login from that region only, buy US u can only LOG IN from a US ip. Once logged in you can switch worlds (US, Europe, what ever) and change language without restrictions.

Hope this answers the people who had the same question as I

This post has been edited by Devilene: Jul 31 2012, 02:44 AM

Pretty simple actually Only if you're from NA or EU that you have to buy specific boxes. If you're not from either region, whichever box you buy will also connect you to NA data center/server. and once inside you can choose any world from eu or na.