I know that Free Software (this means the concept of free as in freedom, not software that does not cost anything) and Open Source have two distinct definitions. In practice though, they turn out to be mostly the same. But I was asking myself, if the minor differences can lead to a software license that is conforming to one definition but not the other? Does such an example exist? And what are the points in either definition, that make them different?
See the examples from my answer to the question "Is Open Source Software a subset of free software?":
Example 1: Free Software, but not Open Source Software
↳ So these early versions of Mozilla are Free Software, but not Open Source Software.
Example 2: Open Source Software, but not Free Software
↳ So Active Agenda is Open Source Software, but not Free Software.
There are various reasons why OSI could approve a license that FSF doesn’t, and vice versa.
The "Approvals" table in the Wikipedia article 'Comparison of free and open-source software licenses' lists cases where only one of FSF and OSI approved a license, and sometimes links to a source that explains why the other organization didn’t approve it.
For example, the Do What the Fuck You Want to Public License (WTFPL) is approved by the FSF, but not by the OSI. In OSI’s Board Meeting Minutes, where this license was discussed, it says:
Mr. Nelson's report includes the following licenses to be discussed and approved/disapproved by the Board.
Title: WTFPL Submission: http://crynwr.com/cgi-bin/ezmlm-cgi?17:mss:634:200902:aglgcgbhmfcheffmdgon License: http://sam.zoy.org/wtfpl/ Comments: It's no different from dedication to the public domain. Author has submitted license approval request -- author is free to make public domain dedication. Although he agrees with the recommendation, Mr. Michlmayr notes that public domain doesn't exist in Europe. Recommend: Reject
They decided to "reject the WFTPL as redundant to the Fair License".
NASA Open Source Agreement is open source but not free software.
Quoted from: http://www.gnu.org/licenses/license-list.html#NASA:-
The NASA Open Source Agreement, version 1.3, is not a free software license because it includes a provision requiring changes to be your “original creation”. Free software development depends on combining code from third parties, and the NASA license doesn't permit this.
We urge you not to use this license. In addition, if you are a United States citizen, please write to NASA and call for the use of a truly free software license.
Also visit wikipedia article in which you can see OSI approved : yes, FSF approved : no
Points to be noted:-
The term “open source” software is used by some people to mean more or less the same category as free software. It is not exactly the same class of software: they accept some licenses that we consider too restrictive, and there are free software licenses they have not accepted. However, the differences in extension of the category are small: nearly all free software is open source, and nearly all open source software is free.
You can see reason is approval by different foundations and their ideas (bold added).
/----------------------------------------------\ / | | \ / | | \ / | | \ | | | Source license is GNU *GPL, Apache, | | original BSD, modified BSD, | free | X11, expat, Python, MPL, etc., | | and executable is not tivoized | open source | | | | \ | | \ | | \ | | / \---------------------------------------------- / | tivoized (tyrant) devices | O | / ----------------------------------------------/
...Even if the executable is made from free source code, the users cannot run modified versions of it, so the executable is nonfree.
The criteria for open source do not recognize this issue; they are concerned solely with the licensing of the source code. Thus, these unmodifiable executables, when made from source code such as Linux that is open source and free, are open source but not free.
quoted from fear of freedom
The philosophy of open source, with its purely practical values, impedes understanding of the deeper ideas of free software; it brings many people into our community, but does not teach them to defend it. That is good, as far as it goes, but it is not enough to make freedom secure. Attracting users to free software takes them just part of the way to becoming defenders of their own freedom.
Yes, it exists, even if you don't count unor's examples of recognized/nonrecognized licenses.
Free but not open source
Legally, offering a service over the Internet already means that you are distributing your software to users. So in this definition, there are tons of examples, for example Google.
But even if this is not the definition you had in mind, there are installable programs which are free to use but not open source. I don't have an exact name in my head, I think Treesheets used to be closed source once, so was the .NET framework and there are probably more, mostly historical, examples. Also many device drivers are available for free but the code is closed.
Open source but not free
If you have a very stringent definition of "not free", this is of course impossible, because open source licenses prohibit you to charge for the source code, so there is always at least one method to obtain the software for free.
But if you change the definition to "the product is generally sold for money, but the code is available under an open source license", then this is available. A prominent example is CrossOver, a gaming platform allowing to run Windows games for Mac and Linux. They have a paid model, I even think that it was a subscription. Their code is GPL licensed, and available for free. Still, there are many people who pay the price, either for the convenience of having the easy install + support, or out of a "support the guys who write the software I use" consideration. I have seen the second one happening in other cases with games, such as people paying high Humble Bundle prices for open sourced games, although sometimes I think the games were open sourced after the sale (sometimes as a direct result of the sale).
The bottom line is that the basic assumption of "nobody will pay for it if they can have it for free" is empirically shown to be as false as many other simplistic assumptions of standard economic theory. We are not Chicago's homo oeconomicus. And we happen to have examples for free-but-not-open as well as open-but-not-free software products. But they are somewhat rare, because 1) people who want to do free prefer the benefits of open source, and 2) people (and especially institutions) who want to do non free are still afraid of monetary disadvantages under open source models (and may be right, if they choose the wrong model).