In today's world of lending, it is often confusing to sort out the differences between brokers, banks, funding companies etc...
Mortgage brokers differ from commercial banks and Savings and Loan Associations because they represent dozens of lenders. They act as home financing 'match makers' by trying to pair you up with the lender who offers a product best suited to your needs. That runs the gamut from no points to some points, from adjustable to fixed interest rates, to hard to place or specialty loans (i.e. bridge loans). Mortgage brokers may either shop your loan with lenders or place it directly.
Lenders, on the other hand, represent one company and their particular loan products. Some lenders work in different lending niches; for example, borrowers with a less than perfect credit rating or loan qualifications.
One of our favorite resources for understanding mortgages is author David Reed's book - Mortgages 101.