I vote for #5, No difference, which is not the same as #4 Can't tell, I think? Basically because most of us are being to ask fill ALL the roles listed below. There is no difference. The lack of education on managements part about the differences is one of the many reasons I started a SharePoint Users Group. One of our goals, lofty as it is, is to help educate managers, employees, users, etc on what the clearly defined roles should be!
In my experience most people that think they fall into #1 are also being tasked with #2 tasks as well and visa versa. Are corporations just getting cheap and trying to squeeze as much value out of each employee or is it truly lack of education? That's the $64k question!!!