Lifecycle, management system and value chain
Three models that appear to describe the same diagram.
The sequence of steps from understanding demand to recalibration. Describes work over time.
The structure of policy, roles, processes and control governing those steps. Describes governance.
The account of how facility effort becomes organisational outcome. Describes causality.
The difference in one sentence
Lifecycle describes when something happens, management system describes who controls it, value chain describes why it has effect.
Why they get conflated
All three are drawn as cycles and all three carry PDCA underneath. The difference lies in the question they answer, not in the shape.
Why it matters
An organisation can run a complete lifecycle without a management system, and be certified without a demonstrable value chain.
How to tell them apart
Ask: does this describe when something happens, who controls it, or why it has effect?