There are some similarities in the responsibilities of interims and management consultants as well as overlap in some of the skillsets. However, there are clear differences between the two:
Implementation. Management consultants tend to consultant and provide guidance and recommendations where an interim will do that and then go on to deliver the proposed solution.
Motivation. It is in the interest of the management consultants to try to offer additional services or extend the length of the project. Interims rely on referrals and having a track record of delivering results quickly, so it is in their interest to do the job needed as efficiently as possible.
Skillset. Management consultants are often selected for project based on their availability. Interims are chosen purely for their specific skillset, reputation, experience and expertise. They will not swap in and out depending on other client work but stay focussed and committed to the assignment from beginning to end.
Control and accountability. Interims report directly to the client working with the internal team to deliver results. Management consultants report to their consultancy house and use the team at their consultancy for resource and support.