Sadly, a lot. Both work to incentivize running up a balance on your credit card. The 0% introductory APR will entice you to make purchases “for free’ (pay no interest). And the rewards can convince you you’re actually coming out ahead.Both will be true in the short run. But if they cause you to run up a balance, the party will be over when the introductory APR ends. Then you’ll be stuck with a high balance credit card, complete with regular interest charges. Worse, if your balance is close to being maxed-out, the rewards won’t be worth much to you anymore.