They basically are pre-orders. You are pre-ordering for when inventory becomes available again for shipment. Procedurally and accounting wise it is the same difference. If you order an iPhone and there is not an inventory item assigned to your order, then it is basically a "pre order." (And doesn't count in sales figures). At that time that an inventory item becomes available and is assigned to your order, it becomes a sale.
9/24/13 at 9:09am