American Express Membership Rewards - Amex consumer charge card

I am going through the rules for Delta Skymiles card from Amex, and at one place it says - if you are ""American Express Consumer Charge Card" then its $40 annual fee, other wise $95.

Can some one please say what is meant by "American express consumer charge card". thanks.

If you have a green card, gold card, platinum card, or centurion charge card you pay a reduceded rate. To make it clear it must be an amex charge card product where the ballance is due every month.