Yes, there are two kinds, so both answers are correct. The bank card (with Chase) gives me a credit balance of 3% back in cash that I can apply to the next month's purchases, when I go to pay for things there's a little radio button asking me if I want to use the credit, similar to a gift balance. The store card (with Amazon directly) just takes 5% off the bill at the time the statement closes.
Note: the amazon store card becomes the default for things like Subscribe and Save. When you apply for the card, Amazon will change the settings of anything you've set up to that new account. It's not a big deal but does require manually resetting if you don't want it that way.