When an item is available for Pre-Order, the publisher has scheduled the item’s release date and is taking orders ahead of that date with the intention of fulfilling those orders as soon as the item is available.
An item on backorder has already been released, but is not currently in stock, and Barnes & Noble has placed an order with the vendor for additional inventory.
On bn.com, you will see different item availability notes based on if the item is on pre-order or backorder.
Pre-Order: This item will be released on (Release Date)
Backorder: Scheduled to ship on (Expected Availability Date)
In either case, if you place an order for one of these items, you will be kept up-to-date on the status of your shipment via email.