Start screen (proper noun)
The full-screen view of Start that includes the list of items, such as apps, websites, and other info that a person can specify and customize. It is what is displayed when the Start button is used.

Start screen (proper noun)
A screen that gives users quick access to recent documents and recommended templates when an Office application starts.

Pin to Start (proper noun)
The UI label for the button on the app bar that affixes a tile to the Start screen.