Named credits are tied to a named license seat and are reserved for a specific, assigned user. They provide a guaranteed personal Monthly Refresh. If a user leaves the organization, the Admin can unassign the named seat and reassign it to a new user. The new user can immediately use any unused credits remaining on that seat; the credits are not held until the next refresh.
Shared pool credits come from a floating license subscription or from a Chaos Credits packages and are added to the Shared pool. All invited users in the organization can draw from this pool, and Admins can set per-user consumption limits (credit limits) if needed.
Note: Credits packages are only available as Shared pool credits. There is no standalone purchase option for named credits - they can only be obtained as part of a named license subscription.