The new private browsing mode goes further than just not saving your browsing history (read: porn sites) ? the added tracking protection means
Firefox also blocks website elements (ads, analytics trackers, and social share buttons) that could track you while you?re surfing the web, and it works on all four platforms. The feature is almost like a built-in ad blocker, though it?s really closer to browser add-ons like Ghostery and Privacy Badger because ads that don?t track you are allowed through.
https://www.mozilla.org/en-US/firefo.../releasenotes/