All other Audit Systems are postmortem method in nature. The reports covers only about, how the frauds and mistakes are done and there is no preventive measures and cannot control wastages.
But In IAS system, since it is an Online Audit, the system automatically controlling frauds and mistakes before their occurrence. Or, the Deviations are made known to the higher authorities through Flash Reports. Also, through proper system , the approvals are done by the Top level Management before that deviated transactions are taken into account.