How does a public ltd complement a private ltd?

The difference between pvt ltd and public ltd company is in the no. of shareholders and transferability of shares. In pvt ltd the minimum no. of shareholders is 2 and maximum is 50 excluding the past and present employees who holds shares . Whereas in public limited the minimum no. of shareholders is 7 and there is no maximum limit.
Public sector company is a company where the central govt or state govt or both of them combined together holds the majority of shares. But in Private sector companies the private individuals or business houses holds the majority of shares.