What’s the difference between a mission and a vision? How’s a purpose different from a goal? Does the corporate mission last forever, or does it change over time? If you’re confused about any or all of these, it’s not your fault. For two decades, business leaders have tossed these terms around with reckless abandon, while experts have defined them in ways that seem to contradict one other.

Here’s a simple model that puts the major concepts of the last 20 years into a clearly defined hierarchy. The next time you address the top-level drivers behind your business or brand.

Notice in the pyramid that mission and vision are on the same level. They’re like unidentical twins that reveal the “how” and the “what” of future success. Most CEOs get this wrong, using mission and vision interchangeably. Also notice that purpose is on a higher level than both mission and vision. That’s because even when the mission isn’t going well and the vision seems like a mirage, a strong purpose will keep people coming back to work day after day.

That’s it. Now you can start building a strategy that all your stakeholders can understand.