I believe my question still remains. If not all projects are employment, when does working on a project become employment? What criteria need to be met?
I believe I answered that very clearly in my last response. One likely works on projects as part of employment. One may work on projects outside of employment. 'Project' does not imply 'employment' though typically 'employment' does imply 'project'.
If you start a business, you legally become employed by that business. If you work on a project without a business, you have not constituted employment. As for interviewing, even if you start a business and work on a project, with no completed product or sales to speak of, I think you'll still have a difficult time claiming legitimacy.