Where Employees Provident Fund serves all salaried employees, the Public Provident Fund serves everyone - the employed, the unemployed, even children and housewives. The access to the fund is also quite easy as any post office and some State Bank of India branches can help you open the fund.
The purpose of a provident fund is to provide individuals some form of savings for their retirement years. Naturally, the EPF and PPF are for long term savings.
Also see: Tax-saving instruments you must know