Explanation:

Public Accounts Committee, as the name suggests is charged with scrutiny of CAG reports on:
Expenses vs earnings of the government - Finance accounts
Actual vs sanctioned expenditure - Appropriation accounts
Accounts of state corporations, manufacturing, trading - Public Undertakings
Estimates Committee, suggests improvements, alternative policies etc. to the government. 
Since it is involved in procedure of spending people's money, hence only those members are allowed who are directly elected by the people ie. Lok sabha members

However, both these committees are advisory in nature and their advices are not binding on the government.