1GB = 1 billion bytes and 1TB = 1 trillion bytes; actual formatted capacity less.
** Trade-in values will vary based on the condition, year and configuration of your trade-in device. You must be at least 18 years old to be eligible to trade in for credit or for an Apple Store Gift Card. Not all devices are eligible for credit. More details are available from Apple’s trade-in partner for trade-in and recycling of eligible devices. Restrictions and limitations may apply. Payments are based on the received device matching the description you provided when your estimate was made. Apple reserves the right to refuse or limit the quantity of any device for any reason.