5 CFR §300.401

1. (a)A commercial recruiting firm is a profit-making entity which, by contract, supplies individual candidates for consideration for specific Federal vacancies, in accordance with the requirements set by the Federal agency.
2. (b)A nonprofit employment service is one legally established as nonprofit under State law. It may be operated, for example, by professional societies, organizations of college graduates, social agencies, or a State or local government. Federal agencies may not, however, use a nonprofit employment service sponsored by a partisan political organization. By contract, a nonprofit employment service supplies individual candidates for consideration for specific Federal vacancies, in accordance with the requirements set by the Federal agency.