Is it a norm in android apps to only have bottom navigation only on parent activities

1. What is the difference between bottom navigation and bottom app bar?

What is the difference between bottom navigation and bottom app bar?

Bottom Navigation is mainly used to navigate between primary destinations in the app. From the above example, the primary navigational tasks - which the user will most often make - is to move between home, messages, and info. Bottom App bar, however, is used to navigate between different sections in the app.