The REAL difference is that if you couldn't pay 20%, you may need to pay extra insurance to cover the rest principle you couldn't pay. Let's say if you pay 10%, creditor may require you to buy insurance to cover the rest 10% to insure their money. After you pay off 20% ofprinciple, you don't need to pay that insurance any more. So, you'd better to know how much that insurance is and whether you could afford it.