A Pre-Qualification is an initial assessment of your credit and the information you provide on your loan application. This basic review by a loan specialist enables them to determine what loan programs might be a good fit based on your goals and qualifications.
A Pre-Approval on other hand, goes beyond the initial review. This process differs from lender to lender. Some lenders only go as far as running your information through an automated underwriting system to confirm you are pre-approved for a loan. Others will go further to identify potential pitfalls upfront by requesting and reviewing supporting documentation.
However, the most dependable pre-approval is one that is issued after an underwriter has reviewed your credit, income and asset documentation.