Lightning pages for the Salesforce mobile app
Key Takeaway
App pages and record pages work in the Salesforce mobile app, but saving an app page doesn't make it available to users: you must activate it.
A Lightning page is a custom layout that you build in the Lightning App Builder from Lightning components, for use in the Salesforce mobile app or Lightning Experience. Admins use app pages and record pages to give mobile users fast access to the records, lists, and actions they use most.
Lightning pages, page layouts and Visualforce pages
Lightning pages sit between page layouts and Visualforce pages. As with a page layout, you add items to the page, but on a Lightning page the items are Lightning components, which give more flexibility. Components can be standard (built by Salesforce), custom, or from AppExchange.