Working in the field I would suggest forensic accounting will focus on entries in the accounting ledgers (general ledger, accounts payable, accounts receivable) whereas forensic audit could have a wider remit across business processes that will likely include non-financial processes.

As to "controlling" fraud, primary responsibility for minimising fraud (as it cannot be completely eliminated) falls to the CEO and whomever he/she delegates it to. In practice I have found forensic audit of business processes can be useful in IDENTIFYING fraud. But beyond the identification, those forensic data findings then need to be actioned by the CEO and management in order to control the occurrence of fraud.