Any time a change is made to an IVR (i.e., name change, new recording, a new node, etc.), an "unpublished" version is created to capture your changes.
You'll see Unpublished draft exists under the Notes column next to the IVR with an "unpublished" version.
You'll also see the status of your IVR from the edit page.
Think of "unpublished" as a "draft" state to hold your changes without going live. Your current IVR configuration will remain until you publish your changes by clicking on Publish.
You can also restore to a previous configuration as needed.