When they get to the closing table to sign the paperwork for their refinanced mortgage loans, the Smiths and the Joneses see two very different sets of numbers because of the different interest rates they were charged over the past 15 years.

Interest paid. The 3.93% rate on the Joneses’ Fannie Mae loan meant they paid $78,882.27 in interest over 15 years, while the Smiths paid $101,177.31—that’s $22,295.04 more.

Principal paid. The two families also repaid different amounts of principal. The Jones’ paid off more of their principal—$57,115.30—while the Smiths repaid only $51,752 of their note because their interest rate was higher.

Amount owed. That higher interest rate also affects how much they still owe on their original mortgage. While the Smiths have to refinance $108,884.70, the Joneses only have $103,303.80 left to pay off—all because Fannie Mae’s guarantee gave them a lower interest rate.