Хорошо описанная разница между открытым и свободным ПО

http://www.naughtycomputer.uk/free_software_better_than_open_source.html

А конкретно, абзац:

    In fact free software a very good term because it is harder
    to explain so you have to explain it properly. Like this:

    "Most software deprives you of the Freedoms to share, modify and
    study, by keeping the human-readable copy of the code secret and/or
    using copyright law to restrict you. This is called nonfree
    software, and is gives the developer control over it's users; this
    makes the program an instrument of unjust power. Free Software is
    software that respects the user's rights to control their computing.
    With Free Software, you can study and modify the code, and share the
    changes with your friends. This is important to society because it
    means we are in control of our tools. Free Software is a matter of
    freedom, not price. How much it costs is irrelevant, freedom is what
    matters. Software that doesn't cost anything is freeware..."

    "Open Source" is too easy to explain because you can just say:

    “Open source is software that publishes the human-readable version
    of the code and gives you permission to study, modify and
    redistribute it.”