Mozilla didn't release the Firefox branding under the same license as the rest of Firefox (and, iirc, the branding license was non-free per the DFSG). So, Debi

Mozilla didn't release the Firefox branding under the same license as the rest of Firefox (and, iirc, the branding license was non-free per the DFSG). So, Debian forked Firefox, Thunderbird and a couple other things and replaced all the branding with the Ice* names and icons. Mozilla eventually gave up and so Debian now distributes Firefox with the Firefox name and branding.