An installment loan is issued in a single lump sum, has a fixed interest rate, and is repaid in equal payments of principal and interest over a set number of years. Once an installment loan is repaid, you have to apply for another loan to get more money. In contrast, revolving credit is money that can be borrowed and repaid repeatedly. You’ll typically only be required to make interest-only payments on revolving credit, although some lenders require you also to repay a small portion of the principal each month. Revolving credit usually has a variable rate.