A pre-qualification is a letter provided to a buyer from a loan officer. It is intended to provide an indication of the mortgage the buyer might qualify for.
A pre-approval letter from a lender, however, is a letter that indicates a conditional commitment to lend. There are always conditions for things not done yet like an appraisal or title work, and possibly conditions related to things a buyer still needs to provide. But it allows the loan originator to firmly state that the buyer qualifies for a specific mortgage amount, provided all conditions are eventually met and, based on an underwriter’s review of their financial information, including their credit report, pay stubs, bank statement, salary, assets and obligations which is documentation provided by the buyer.