A business delegate is generally thought of as a plug-in that is given to the client developer.This "plug-in" can do service lookups and searches on behalf of the client developer. Very smart if you have a Swing or Servlet Developer that doesn't know ejbs.
A session facade is a session bean that is much like the delegate but resides on the server and is used to encapsulate course services so that network can be held to a minimum.
A business-delegate can call a session facade which in turn can call an entity bean