These features were ripped out of Firefox to make it a more focused, speedy Web browser. Firefox was the evolution of the “Mozilla Application Suite,” which also contained email, IRC chat, HTML-editing, and newsgroup capabilities. SeaMonkey isn’t technically based on Firefox, but it’s closely related. It also uses its own configuration directory, unlike Waterfox.
Pale Moon diverges from Firefox in removing accessibility and parental control options, while modifying the default interface settings to be similar to earlier versions of Firefox - it has a bookmark toolbar and status bar by default.
Pale Moon is another “optimized” build of Firefox for Windows, but it also has a 32-bit version. If you decide to uninstall it, don’t select the “Remove my personal data” option unless you also want to delete your Firefox data. Waterfox uses the same profile data Firefox does, so switching to Waterfox is easy.