"...Different types of transactions, different Annual Percentage Rates (APRs)
A single credit card account can have several different APRs. For example, your credit card issuer may charge one APR for purchases and another for balance transfers. Also, some APRs can vary over time. Issuers may encourage you to use your card by offering promotional APRs that give you a lower interest rate on certain types of transactions for a set period of time. When the promotional period is over, the APR may adjust to a higher level, raising the cost of carrying a monthly balance. Used wisely, however, these low promotional rates can save you money.
All of the APR information is clearly displayed in a comparison box or chart in your credit card Agreement and on the issuer's credit card site. Be sure to check it thoroughly...