A Business Rule Engine is one part of a complete system for handling all the things involved in working with rules. Admittedly, it’s an important part, but it deals only with execution… which rules need to be executed in what order? The big enterprise-oriented players are concerned with a lot more… There’s all the development and testing; linking up to data sources and other applications; measuring and reporting; deployment to different computing environments; making rule maintenance easy; looking for conflicts; and so on.
Business rules management systems gives business users and analysts the ability to make routine changes and updates to critical business systems while freeing IT resources to concentrate on higher value-add projects and initiatives. The idea is that, using common business terms and familiar interfaces, business users and analysts can update business strategies across enterprise information systems. This control of the business logic embedded in IT systems allows business users to alter application behavior without IT assistance.
So Business rules management systems require a powerful enterprise repository, intuitive rule maintenance applications for business users, version control, reporting and multi-platform deployment as well as the Business Rules Engine itself.
Only the biggest and most established of the pure-play rule software vendors can hope to cover all of this, so they try to establish themselves with a label that calls attention to the differences. I think Blaze Advisor started using the “Business Rules Management System” label and then ILOG decided to adopt it. I expect other vendors to start using it to try and group themselves with the leaders.