From Guild Wars 2 Wiki
The following types of binding exist:
- Account Bound - These items can only be used on the player's account. They can be passed between characters via the Account vault.
- Soulbound - A soulbound item can only be used by the character it's bound to. This binding cannot be removed at a later date, even if the character is deleted.
- Soulbound on Use - Equipping the item on a character will switch the item's property to Soulbound.
- Soulbound on Acquire - The item will be Soulbound when placed in a character's inventory.