The user has to select from a pool of items or options. What items are displayed and their order or sequence may have some relevance to the user.
In some cases this list must be accessed on a regular basis, on others very rarely.
Determine when the user will need to access the pool of available items.
If the typical user in a typical context will need to know what items are selected, but is unlikely to add or remove items from the list, use the Picker Dialog.
If it is likely that the items will be changed on a regular basis, use Two Lists with Arrow Buttons.
with Arrow Buttons]]