Being almost a synonym for “free software”, the term “Open Source” has some advantages, but also some disadvantages.
The term “Open Source software” was introduced in 1998 to denote software which conforms to the Open Source definition. This definition was derived from the free software guidelines of the Debian project. For this reason, “Open Source software“ denotes essentially the same software as the term “free software”.
The term “free software” has an ambiguity problem. Besides the intended meaning “software which gives you certain freedoms”, it can also be understood as “gratis software”. This is a constant source of misunderstandings and of acceptance problems in the business sector.
The term “Open Source” was introduced for the explicit purpose to solve this problem and to create a “marketing name” for free software that should be more acceptable for businesses.
Unfortunately the term “Open Source” brings along some misunderstandings of its own: taken verbatim, “open source” denotes software where you may look at the source code. This is not wrong but it is to weak because it does not say anything about your right, as the user of the software, to make use of the source code.
Exploitation of this ambiguity might look absurd at first glance. Nevertheless it is actually being done by those who want to profit from the success of Open Source and free software, without ever contributing to it.
With the term “free software” the intended meaning is one of two valid meanings. With “Open Source” the intended meaning goes beyond the verbatim meaning. For the short term, the danger of misunderstandings goes down; in the long run it goes up.
This holds in particular in the English language where “open source” has a verbatim meaning. When “Open Source” is used in the German language as a fixed term, it does not have carry any meaning besides the intended one, so it can be useful to bring an interested party closer to the concepts of free software, provided that one does not stop at that point.
In other languages—e.g. French and Spanish—the term “free software”—software libre—stands for “freedom” unambiguously. In those languages there is no need for an additional marketing term.
Technical Or Political?
Another difference between both terms is that “Open Source” is politically neutral, while “free software” carries the political concept of “freedom”. For this reason, “Open Source” is easier to “sell” than “free software”.
This advantage is also a disadvantage: by cutting away the political roots one spoils the sustainability. By using a “non-political” term, the political message behind the concepts of free software gets hidden. Someone who uses or develops Open Source Software just for practical considerations will not pass on the social implications of free software—for instance the civil right of informational self-determination.
But someone who is not aware of his rights will not defend them. He will be an easy prey of anyone who asks him to give up his rights for some short-term practical advantage.
Here again, the short-term advantage of better acceptance is surpassed by a long-term disadvantage.
Read more about the difference between the terms free software and Open Source in the article Why “Free Software” is better than “Open Source” by Richard Stallman.