Most organisations have Strategic Objectives. For many commercial organisations, these focus around the creation of value - whether this is through profit (costs down, income up), increased assets (IP and patents, land or companies that increase in value), or simply share price. To achieve each of these strategic objectives may require a number of programmes - for example cutting costs may involve investment, and increasing income may involve Public Relations. Each programme may be made up of multiple projects, which are in effect the bite-sized activities (some running to an investment of £millions) which deliver capability.
For public service organisations (public sector, NHS, community and voluntary, not-for-profit), the Strategic Objectives typically revolve around delivering improvements for the population that they serve, whether it is quality of life, healthy outcomes, or a safe community. Once again, to create a safe community may require improved public awareness, housing, policing, and activities that a target audience can contribute to. Improving public awareness is not a one-time and it's done thing - it may involve lots of individual projects running one after the other.
So the Strategic Objectives (plus the existing services) are the intended outcome of the Portfolio - the sum total of all change initiatives alingned to the outcomes that the organisation intends to achieve.
Then the programmes represent the streams of work that will deliver these outcomes. And within them, individual projects deliver capability. Benefits Management (on the right hand side) ensures you get the results that you set out to get, not just an on-time on-budget project and unused capability
This diagram is based on John Thorp's work and "The Information Paradox".
With the P3M approach combined with Benefits management, you can expect far more success, far more investments that either pay for themselves, or that you identify they aren't going to early enough to save the investment to pay for something else (if everything works, you aren't being ambitious enough!). It isn't P times 3, it's P to the power of 3 (P3)