Earlier quoted context omitted.
Is there a clearer more understandable word? Your definition of 'distribution' sounds like something much more specific (changes to binaries?) than mine.
At risk of putting words in the another poster's mouth, I don't think the idea was that a distribution needs to have changes to binaries, just that it has to include the whole thing. I think the notion is that since you don't get your build of Emacs as part of Spacemacs, Spacemacs isn't a distribution of Emacs. I tend to agree. I think it could be a distribution of Emacs even if it were just upstream Emacs plus a sim…
Can found more explanations on reddit for the bravest :-)