Explanation
Graphical user interface, application Description automatically generated

Box 1: App designer
As an app maker, you can create and edit public views by using Power Apps.
Box 2: Site Map designer
Site maps define the navigation for your app. Create a site map for your app with ease by using the tile-based site map designer.
Reference:
https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/create-edit-views-app-designer
https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/create-site-map-app