Most lenders offer you a mortgage, where you have to repay both the original loan amount and interest through monthly payments. Interest is the biggest cost that you have to incur on a mortgage. As most of your payments will go toward the interest on the mortgage. A good deal on a mortgage is one that offers you a lower interest rate and easy repayment terms.
You can compare the rates and other terms offered by different lenders to get an idea of what the loan will cost you. By doing this, you will find that most lenders offer pretty much the same basic terms. This is because they are all regulated to a certain extent by the government. However, there could be significant differences in several other charges like closing costs, prepayment fees, appraisal costs, legal fees, etc.