Affiliates simply refer the traders to the brokerage firm. The affiliate might be compensated on a Cost Per Action (CPA) or revenue share model. The affiliate referral process can easily be automated. After a referral takes place; the affiliate has no obligation. IBs provide real services to the traders they refer. It is much less likely the IB will have any part of the process automated. They are providing services before the referral as well as after the referral. In summary, affiliates are less involved in the services of the brokerage firm, while IBs use their services as a foundation for the partnership.