In Debian, [Iceweasel is Firefox][1] once again, since [March 10, 2016][2]. There's an [Iceweasel branding][3] add-on which can be used to restore the Iceweasel branding.

There are some non-cosmetic differences between Mozilla's version and Debian's; you can see all the patches [here][4]. You'll find changes which disable "phone-home" features (Firefox health report), change the way plugins and extensions are handled to work better in the context of a distribution with packaged plugins and extensions... There are also a series of bug fixes backported from work-in-progress upstream versions.

These are the kinds of changes you could find in any package in Debian (the old branding changes weren't, of course, although quite a few Debian packages include minor branding changes — *e.g.* adding a "Debian" mention in version numbers in `gcc` and Wine). The Chromium package for example also disables various "phone-home" features; many packages include backported bug fixes, and changes to integrate the software into the distribution.


  [1]: https://lwn.net/Articles/676799/
  [2]: http://anonscm.debian.org/cgit/pkg-mozilla/iceweasel.git/commit/debian?id=15cc4433d63e2aa8e89339c248634c52d4e95789
  [3]: https://addons.mozilla.org/en-US/firefox/addon/iceweasel-branding/
  [4]: http://anonscm.debian.org/cgit/pkg-mozilla/iceweasel.git/tree/debian/patches