What is the difference between public companies and public sector?

Definition of Public Companies

Public companies are those businesses owned by individuals (and not by a government).

Definition of Publicly-Held Corporation

If a public company is a corporation whose stock is traded on a stock exchange, it is said that the stock is publicly traded or that the corporation is a publicly-held corporation or a publicly-traded corporation.

Definition of Public Sector

Public sector refers to government-owned organizations and government-provided services.