Prequalifying for a home loan means that you've taken an informal look at your finances to determine how much you can afford and whether you meet the minimum requirements to take out a mortgage. This can be done without going too deeply into your financial information. On the other hand, a preapproval is given when you complete a full mortgage application: the lender accesses your full credit report and gives you a written offer for a loan at a specific interest rate, subject to your finding a home to buy and completing the underwriting process. Having a prequalification or preapproval letter can make you a more compelling candidate to buy a home and may put you ahead of other parties making an offer.