Marjan International Corp. sells handmade oriental rugs. V. K. Putman, Inc., is a Montana trucking company. Marjan delivered valuable rugs to Putman for shipment from New York City to Tacoma, Washington. Unfortunately, there were several delays in transit. The truck driver encountered snow storms and closed roads. His truck also overheated and required repairs in a garage. Before the driver resumed the trip, he stopped to pick up and load other goods. When the truck finally arrived in Tacoma, two bales of rugs were missing. Marjan sued, on the grounds that Putman was a common carrier, but Putman claimed it was a contract carrier. What difference does it make whether Putman was a common carrier or a contract carrier, and how is that determined?