On what basis do we differentiate public sector from private sector?

The public and private sector is differentiated on the basis of "Ownership" of the enterprises. In the public sector, the government owns most of the assets and provides all the services. In the private sector, ownership of assets and delivery of services is in the hands of private individuals or companies. Railways or post office is an example of the public sector whereas companies like Tata Iron and Steel Company Limited (TISCO) or Reliance Industries Limited (RIL) are privately owned.