What is the difference between deployment and release, and how do feature flags help?

In production deployment and release have separate evidence and controls. The pipeline proves the artifact is healthy with the feature off, while rollout proves user and business outcomes for controlled cohorts. Flags are not authorization boundaries and do not make incompatible database or event changes safe. I define owner, targeting policy, default and failure behavior, kill-switch access, propagation delay, metrics, expiry, and removal task. Cohort identity is stable enough for comparison without exposing private targeting data. If the disabled path must remain for months, it is treated as a supported product mode rather than temporary release machinery.