Card: With credit card payments, the payment is processed instantly and activation serial numbers are issued by email same day.  Subscription payments are automatically processed monthly or annually until cancelled.  

US bank account:  With this option, the customer enters their bank information to set up an automated ACH payment directly from their bank account.  The payment is processed within 4 days and activation serial numbers are issued by email once the payment has processed.  Subscription payments are automatically processed monthly or annually until cancelled.  There is no additional cost (bank fees) for the customer with this option.