On a serious note Stallman continuously points out that he does not support the open source movement and that free/libre software and open source software are two different concepts.
He does frequently do this, but I don't think its actually substantively true -- Free Software and Open Source software are basically identical concepts, however, the FSF has a strong commitment to combating non-Free software while the open source movement is more about promoting open source software. The big difference in the movements isn't really "Free" vs. "Open Source", its opposing things that don't meet our ideal (with promoting certain things that do meet the ideal as sometimes an instrumental means to that) vs. promoting things that do meet our ideal (with opposing certain things that don't as sometimes an instrumental means to that).
"Free Software" terminology emphasizes its ethical necessity to maintain a free society.
One is technical, one is political/ideological. Open source advocates don't care about politics, Free software advocates think technical superiority is unimportant in a non-free society.
Stallman's own words on this distinction in this video: https://www.youtube.com/watch?v=Ag1AKIl_2GM
Whether or not a user even knows of this tension, or of the open/closed source status of the code they run, does not exclude whether they may experience benefits. I think this because open-sourcing code does not only increase one's own personal freedom (which is unlikely to be exercised alone due to the magnitude of the task), but more realistically it allows the opportunity for an outside skilled individual or group to be looking over the code, and the benefits can be transferred to all users of the software.
It is akin to a person's relationship to the law, where legal writing is not designed for common consumption, but professionals or organizations may digest and disseminate the data to interested groups. While much of legal code may be away from the searchlights of society or its groups, at the very least, when the situation calls upon it, we may look when we want to. It is not requested on a need-to-know basis where we have burden of proof.
E.g.:
In practice, open source stands for criteria a little weaker than those of free software. As far as we know, all existing free software would qualify as open source. Nearly all open source software is free software, but there are exceptions. First, some open source licenses are too restrictive, so they do not qualify as free licenses. Fortunately, few programs use those licenses.
Second, and more important, many products containing computers (including many Android devices) come with executable programs that correspond to free software source code, but the devices do not allow the user to install modified versions of those executables; only one special company has the power to modify them. We call these devices “tyrants”, and the practice is called “tivoization” after the product where we first saw it. These executables are not free software even though their source code is free software. The criteria for open source do not recognize this issue; they are concerned solely with the licensing of the source code.
https://www.gnu.org/philosophy/open-source-misses-the-point....
https://www.gnu.org/philosophy/free-software-for-freedom.htm...
No, they're not. Software released under the BSD and GPL licenses would both be considered "open source", but only the latter is Free (per RMS' and FSF's definitions of "Free"), for many significant reasons.
[Update: I stand corrected. Thanks for that.]
Well, no. All three versions of the BSD license are recognized by the FSF as "free software licenses"; only two of them are OSI-approved "Open Source" licenses,
1. The original four-clause license, which is neither an OSI approved Open Source license (apparently its never been submitted for review -- OSI, unlike FSF, does its reviews based on submissions, rather than on its own initiative) [0] but is an FSF-recognized Free Software license. [1]
2. The three-clause BSD license, which is both an OSI approved Open Source license [2] and recognized by the FSF as "a lax, permissive non-copyleft free software license, compatible with the GNU GPL." [3]
3. The two-clause BSD license, which is both an OSI approved Open Source license [4] and recognized by the FSF as "a lax, permissive non-copyleft free software license, compatible with the GNU GPL." [5]
[0] http://opensource.org/licenses/BSD-3-Clause ("The original license used on BSD Unix had four clauses. [...] The four clause license has not been approved by OSI.")
[1] https://www.gnu.org/licenses/license-list.html#OriginalBSD
[2] http://opensource.org/licenses/BSD-3-Clause
[3] https://www.gnu.org/licenses/license-list.html#ModifiedBSD