There is a lot of discussion and confusion on whether a service desk and a help desk are the same thing. Can the terms be used interchangeably? Is it just a matter of preference?
Most non-IT employees are going to call it the help desk, or just the IT department. I do not see a movement away from this. However, for those in the IT industry, a service desk is much more than a help desk. In 2007 when ITIL v3 was released, it used the term service desk to describe the departments that encompass all of the best-practices found in the ITIL library, including important topics like service strategy and design.
Building on that foundation from ITIL, a typical help desk would tend to focus on the needs of the end-users and answering questions that could be unrelated to IT. In contrast, a service desk is concerned with the needs of the organization. It is important to also keep in mind that the move to the word service desk is in relation to ITIL. If you're using ITIL best-practices, calling yourself a help-desk is seen as selling your department short since a service desk encompasses a help desk - a part of the whole if you will. A service desk plans out how to keep all facets of IT running, not only dealing with issues as they arise.
If you have any further opinion on this topic we would love to get some discussion going.