What is the difference between a voucher and a coupon?

Coupons entitle you to a benefit described on the specific coupon. A Clubcard voucher can be used for the purchase of any product(s) except the ones listed in the GTC and its value is deducted from the total amount of the basket. You can only validate your Clubcard vouchers using your own Clubcard at the same time. In case of printed vouchers the last 4 digits of your Clubcard number are displayed so that you can keep track of which card the discounts belong to.