Who is and who is not a volunteer?

I hope to get some discusson going on this item. I'd like opinions as to who is and who is not a volunteer.  The organization I work for has several hundred volunteers and others from local groups and organizations who contribute to its activities. Some staff (including senior ones) consider people who are on work placements as volunteers, likewise those who are student placements and internships (whatever that means).  Being a bit old school, I don't - what do others thinK?

My feeling is that volunteers are unpaid, give their time freely and benefit the community. If there is some payment or benefit - as in contributing to their university/college course - involved then I don't feel they are volunteers in the true sense - but in a category of their own. 

Some student placements are a requirement of the course and often involve regular progress reports from the project.  Work placements can involve payment to the person involved and or to the project. The term 'mutuality of obligation' comes to mind.

Really like to hear what others think about this.

jaybee