Lightning page types in App Builder
Key Takeaway
Choose the right Lightning page type when you create the page, because you can't change the type after you set it.
The Lightning App Builder is a point-and-click tool for building several types of Lightning pages. Each type is meant for a different place in Salesforce. The type you pick decides how actions work on the page and where the page can be used, such as Lightning Experience, the Salesforce mobile app, or an email client.
What a Lightning page is
A Lightning page is a custom layout made of regions that hold Lightning components. The template you choose when you create the page divides it into regions and controls how it displays on each device.
Lightning pages sit between page layouts and Visualforce pages. As with a page layout, you add items to a Lightning page. Those items are Lightning components rather than fields or Visualforce components, which gives you more flexibility.