Conceptually similar, both the audits intend to help the auditee in making decisions, to monitor and improve the efficiency and effectiveness of the internal controls, procedures followed by the audited company and so on. The only differences between the two are -
Concurrent audit, as the name suggests, is a regular, ongoing process and is performed side by side with the operations of the audited entity, whereas internal audits can be periodic.
The concurrent audit report may not be produced in the end but the internal audit report is always there.
Concurrent audit is carried out by an independent Chartered Accountant whereas internal audit is done by internal audit department.