These two concepts are commonly confused. That's why sometimes business cannot decide, which service it needs at the current stage.
Our colleagues in the financial sector have agreed to clarify these two notions for us as market standards in this sector have been formed quite a while ago in terms of both legal regulations clients' awareness.
For example, the company is going to have a tax audit. To prepare for it, company invites an auditor who checks if the documents are correct, if the reporting meets the existing standards, if there are no grounds for penalties or presenting administrative (or even criminal) charges and comes up with the relevant changes to eliminate all inconsistencies in a short time. That's a comprehensive scope of the auditor's responsibilities.
Consulting is a more advanced activity. It is no longer aimed at correcting the consequences, but at building the right processes. How to avoid any mistakes at work? How to achieve business goals? How to rebuild the system to meet new conditions?
In the IT sector, the situation is exactly the same: IT audit is aimed at finding existing and potential errors, whereas
IT consulting is aimed at achieving strategic and tactical goals within the digital transformation framework. With one reservation: in the IT consulting the achievement of business goals is considered from the point of view of information technology.