How is the delivery system of a public organization different than that of a private organization?
The differences are centered on motivations, and rule structure.
Private organizations can be influenced to follow budgets and schedules much more than public organizations. Public organations have to show more openness, and transparent accountablity, and can be influenced to a great degree by political influence.
My own experience is that private organizations, in competition with each other, tend to focus on customers more to deliver the services efficently, as compared to non-competitive public or private organizations.