The interest rate is the cost you will pay to borrow the money for a mortgage. It does not include fees or other charges you may pay to obtain the mortgage.
The Annual Percentage Rate (APR) is the total cost of the loan, other charges or fees and is calculated by spreading the upfront costs over the life of the loan and expressing this as a percentage of the loan amount that you pay each year.
The APR reflects not only the interest rate but also any points, mortgage origination fees, and other charges that you pay to get the loan.