Internal auditors will investigate the issues related to the corporate practises and risks of the company, while external auditors will review the financial reports and give an opinion on the company's financial statements. Internal audits are carried out during the year, while a single annual audit is performed by external auditors.
Though independent of the activities they audit, internal auditors are an integral part of the enterprise, providing constant monitoring and review of all activities. External auditors, on the other hand, are independent of the company and have an annual opinion on the accounts.