Return of goods is possible in case of

Return of goods is a fundamental characteristic of bailment - the bailor delivers goods to the bailee for a specific purpose, and the goods must be returned (or dealt with as directed) after that purpose is accomplished. In a sale, ownership transfers permanently to the buyer - there's no return obligation. In an exchange, ownership also transfers (just with different consideration). Only bailment inherently involves returning the goods after the temporary purpose is fulfilled.