A product change is simply moving your account from one credit card to another offered by the same company or bank.
For example, let’s say you have the CardNamediscontinued, and, since you’re traveling less, you’d like to downgrade to the no-annual-fee CardNamediscontinued instead (Citi is a CardRatings advertiser; See Rates and Fees for the Platinum Select card). A product change would move your existing account from the annual fee Platinum Select card to the no-annual-fee Mileup version instead.
This is different than submitting an application for a new Mileup account and closing your other card, and, in many cases, is a better option. It’s generally easy to accomplish with a call to your bank’s customer service line.