A Person is a real human. An Actor is an identity capable of performing a recorded action. A User Identity is the authenticated identity managed by the approved authentication boundary.
Why the distinction matters
One person may have more than one organizational affiliation over time. A service or agent may perform an action without being a human person. An authenticated user may lose future access while their historical approvals and actions must remain attributable.
The current system implements Actors, authentication identities, organization membership, and scoped permissions. “Person” is useful domain vocabulary for keeping the human independent from those technical relationships, but it is not yet a universal standalone aggregate across every module.
Roles and affiliations answer how someone relates to an organization or account. Permissions answer which actions they may perform. Neither should be inferred solely from an email address.