Most leadership assessments tell you what you already know. The point of an assessment is to show you where you are succeeding and failing in ways that are not obvious to you.
Some of what we most need to learn about our own leadership is exactly the part we cannot see. So we build assessments to reveal what a leader can’t see. An assessment gives you evidence. A diagnosis reads that evidence in context, across several sources, to work out what pattern is operating.
You can read the full thinking behind this work in Diagnosing Leadership: Assessments That Change How You Lead.