Models submitted by users are initially available only to them and to users with additional access rights such as administrators. A model can be refined over time by its contributors, through the update process. Users can choose to publish a version of a model, which must be the latest version of the model at the time of publishing. Users with access rights viewing the model would be able to see all versions of the model, while other users (whether logged-in or anonymous) would only be able to view the published versions.
An example of this is shown below, where a model has four versions. A user with access rights to the model is able to see all four versions in the history tab, and is able to view each of them. Other users will only see the published versions of the model.