[jordigh]

There isn't a difference other than emphasis. It refers to the same set of software, but describes this same set of software differently. It's like saying "African American" or "black". The intended meaning is the same set of people.

Indeed, the term "open source" was coined as a marketing term for promoting free software:

http://jordi.inversethought.com/blog/5-things-we-have-forgot...

edit: sigh, every time I say there's no difference I have to contend with the downvotes. Go read my blog post above, please.

[vezzy-fnord]

No, the difference is in how the arguments are derived. Free software uses ethical arguments, whereas open source uses consequentialist claims about software quality, "many eyes catching bugs" and business value.