When making a purchase offer on a home (unless you are buying in cash) you need to have proof that you are qualified for the loan. To do this you need to show a letter to the seller and/or their agent.
Prequalification – This means you have spoken with a lender and the lender is willing to provide a written statement that they believe you will qualify for a loan. It only takes a few minutes and can be done over the phone. This is not as strong as preapproval.
Preapproval –You get preapproved for a loan by submitting a formal loan application that is then verified by the lender. Preapproval makes you look like a cash buyer in the eyes of a seller and gives you more negotiating power.