For users installing Firefox 56 for the first time Mozilla to show onboarding overlay which appears when you click on the fox icon in about:home or new tab page, which contains 5 tours for existing non-photon features such as private browsing, add-ons, Customize, one-click search and Default Browser.
Photon team to add additional tours to onboarding overlay in Firefox 57 with which they ship Photon design. These tours will introduce new photon features. Users who don’t want to see the tour will be allowed to hide the tour with a checkbox. At present, you can check the photon onboarding tour in latest Firefox Nightly.
Do note, currently, Nightly has Photon UI enabled by default, so if you want to see non-Photon designed Firefox 56 tour, you need to flip the preference ‘browser.photon.structure.enabled’ value to false.