Drop-shipping is where products are packaged and delivered direct to the consumer from the manufacturer. The products bypass the retailer.
It eliminates the need for retailers to hold stock and removes the shipping process from manufacturer to retailer. It is a more time and cost efficient process, however complications may arise in regards to quality control.
Drop-shipping is effectively a partnership between a wholesaler and a retailer (business). The wholesaler manages the stock/products and the retailer sends through the order and shipping details to fulfil the transaction.
Private label shipping means that retailers can drop-ship without the customer being aware of it.