Preapproval vs Prequalification
Prequalification happens early in the homebuying process.  When you get prequalified for a mortgage, you are getting an estimate of what you may be able to borrow.  During the prequalification process, you may learn about different mortgage options to find the right fit for your personal situation, when working with your mortgage broker.
Preapproval is a closer step to being confirmed for an actual mortgage.  You complete a mortgage application and your mortgage broker will verify the information you provide.  You will also have your credit checked.  Once preapproved, you will receive a preapproval letter, which is not a commitment, but an offer that lets you know how much you can borrow.  Preapproval letters are usually good for 90 days.