The difference between the CAG and the CGA is summed up in the table:
Office of CAG
Office of CGA
It is an independent body.
It is under the Department of Expenditure in the Finance Ministry.
It is a constitutional body.
It is not a constitutional body.
It audits the accounts and related activities of the 3 tiers of government: Federal, Provincial, and Local.
It is the Principal Accounting Adviser to the Government of India.