Hi Heli,
The shares of a Private Limited Company are closely held, i.e., the ownership is controlled by a few persons (could be a natural person or an artificial person like company, trust, etc.,). Also, since the shares of a private limited company are closely held, the reporting structure and regulatory framework for maintaning a Private Limited Company is consideraly more easier, when compared to a Public Limited Company.
The shares of a Public Limited Company on the other hand are held by a large number of people and the shares of Public Limited Companies are traded on a stock exchange like the BSE / NSE. Since, a large number of people from the public are invested in a public limited company, the SEBI is also involved in monitoring a Public Limited Company and the requirements of reporting are much more stringent.
Hope this helps!