E-pin codes and account top-ups: what is the difference?

A code you redeem and a top-up applied to your account are not the same thing. Which one you are buying, what is asked of you, and which suits you.
Digital goods arrive in two different ways, and confusing them causes most of the trouble.
An e-pin code
You are given a code and you redeem it yourself. Gift cards, game keys and wallet codes all work this way.
The advantage: you never hand your account details to anybody. The code is yours, to use on whichever account you like, whenever you like — you can give it as a gift.
Everything we sell is an e-pin code. We do not sign into your account, we do not load anything on your behalf, and we never ask for your password.
An account top-up
Some products have no code; the balance is applied directly to a game account. For those you are asked for a player ID — your in-game id, sometimes a server or character name.
Not a password. Only the player number that is public anyway. If somewhere is asking for your password, it is not us.
How to tell which you are buying
If the order asks you for something — a player id, a username — the product is a top-up. If it asks for nothing, you are getting a code.
The product page says so too.
Care with top-up orders
If the id you give is wrong, the top-up cannot be reversed. The balance has gone to that account. Check your number in the game before ordering, and copy and paste it.
If you gave the correct id and the top-up still could not be applied, the amount is refunded to your wallet the same day.
Which is better
It depends. A code keeps control with you and can be given away. A top-up is fewer steps: you give your id, the balance arrives, and there is no code to redeem.
The region rule applies to both in exactly the same way: a code and a top-up each work only with an account in the right region.