this is a stupid question, I know...

Interest rate is the actual rate you see on your note. APR is the rate calculated after you consider how much youir closing costs are. The lender will keep the same pmt. but lower your loan size by the same amount of your APR costs in the equation. Therefore if you have the same pmt., lower loan size, and same term your rate must change.It is Calculus. That is the best way I can explain it.

You are not alone. APR is theory is supposed to be a great tool in your home loan decision process. In reality, it is confusing, can be very misleading, and is usually a poor way to choose your loan. I have a great article about "What is APR" at https://JoeMetzler.com/what-is-apr/ I lend in MN, WI , SD. NMLS274132