Blair Automotive performed mechanic services for two customers. The first customer owed $5,280 for services, so Blair Automotive made them sign a written promise to pay in full after six months with an annual interest rate of 3.5%. The second customer owed $326 for services, so Blair Automotive plans to send them a bill within the next two weeks, due within 30 days of receipt of the bill. What is the difference between these two transactions?