I agree with you that the current role is the most interesting thing about the actor most of the time. Actor == role won't go far wrong, I think. If you would have different use case flows or stories for two roles, it's probably not be helpful to know they are really the same person.
Some teams go as far as to make up imaginary individuals in each role with different skills: Bob uses the system all day every day and knows the business inside-out, Marge is an occasional user who needs more help. Would you have different use case flows or stories for these two people?
My current project has some interesting wrinkles, though. There is special functionality to support people who can play multiple roles. Right now we subtly make them identify their "current role" at the start of an activity, but the future may hold requirements to let them play two roles in the same activity scope.
What does your project do with knowledge about different actors? Set up security rights, alter flows, anything unusual? [ June 24, 2005: Message edited by: Stan James ]
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
Individuals can change roles in the middle of a use case. For example, consider enrolling in a university. At the beginning of the "Enroll in University" use case the person is an applicant. If they're succesful, at the end of the use case they're now a student.