Internal help desk software is a different tool than the helpdesk you use for customer support. Unlike customer service help desks, internal help desk software is designed to support your own team. If you want to provide a service desk for the people in your organization, internal help desk platforms provide a virtual solution with a central repository for internal communications about issues and a knowledge base of relevant information for automating workflow.
There is a lot of crossover between customer and team help desks, so you can expect most software to provide support for both. Some of the most common internal help desk tools provide support for IT and HR departments.