A Public Company has seven or more members and can engage public to subscribe to its shares. A subsidiary company of a Public company is deemed to be a Public company.
A Private company is an organization which limits its number of members to 200 and cannot engage public to subscribe to its shares. The Companies Act, 2013 provides for converting a Public Company to a Private Company by change the MOA and AOA of the company.
The main improvment of Public Company is that it can raise capital at a large scale without impending banking system and reducing debt whereas Private Companies which are privately owned, all the reserves are raised by existing members, shareholders and promoters. If a Private company goes public then the risk is also shared among the shareholders. Public companies once recorded, get indirect promotions and backing through stock exchange websites where their stocks are recorded.