"With this release, the team has also made a 64-bit build
available for the first time, although the 32-bit version remains
the default download option. While two architectures are now
supported, there's only one root operating system: the days of
choosing between Firefox and Chromium are gone, with Chromium
winning out as the default browser.
"The primary reason for this is Ice, a site-specific browser
based on Chromium and created by Kendall Weaver for the Peppermint
project. Designed to make web apps feel more like a desktop
install, it replaces the now-defunct Prism project and makes the
Firefox spin redundant."