Credit score, Loan-To-Value and Loan Amount are going to be the 3 main factors which will adjust from we call the Par Rate. Every lender will make different adjustments to a going interest rate based on how you specifically structure your loan. From that you take into account the loan officer's profit. Assuming 2 lenders had identical par rates and adjustments to a loan, the reason one loan may be priced higher compared to another could simply be the LO wants to make more money off of your loan.
By the way, in this market, most lenders would kill to have borrowers with any credit score above 720.