Most people are surprised to find that the pesticides regularly used by professionals are often the same as general use products available to homeowners. Licensed professionals may occasionally use restricted-use products (materials not available to the general public) to solve pest problems that are not responsive to general use products and which may require more sophisticated application technology. These few restricted-use products require extra care and precaution by those who handle the concentrated material when preparing application mixes. Therefore, only certified applicators may purchase and use or supervise the application of restricted-use products.Source: pestfacts.org