What's the Difference Between Long Brand Positioning Statement and Short Brand Positionation Statement?

When I think of my brand, I think of A, B, and C. There's a much tighter, clearer, old-fashioned positioning statement at the heart of short activations that needs to be put in place. What should the client brief contain, and what should it avoid? Don't pre-specify tactics or creative. Clients have no strategy, but they have very clear ideas on what they want from tactics.