Open source and free software mean the same thing. There are philosophical differences between the two groups, but the great majority of software to which the definition of open source applies would also fit the Free Software Foundation’s definition of free software.
Most people have been thinking about software from a vendor-centric viewpoint. And Microsoft is the first model that comes to one’s mind. But Microsoft model accounts for only a minority of the software that is made and used in business. Around 30% of the software that is written is sold as software. Packaged software and other sectors share different parts of the industry, as seen in the appendix section.[1] Most software is not sold at all. It is developed directly for its customer, by the customer’s own employees or by consultants who bill for the service of software creation rather than for the end product.
[1] See Appendix no. 5