I think it is maybe because there are lots of different ways of assigning roles now, not just manually by the teacher - so you have enrolled users (which is a bit of a misnomer) for manual enrolments and and enrolment methods for others. Just guessing though.
Roles and permissions
Admin can't assign roles in Moodle 2.0.1
הדיון ננעל, כך שלא ניתן יותר להגיב אליו.