Difference between Push Notifications and In-App Messages.
Push is more simplified and allows you to quickly broadcast a message to the user’s devices home screen when locked or when the user is using a different App. Push does have some limitations with customization.
In-App Messages are used within the App to display a message to the user based on interaction, data and triggers. In-App Messages help build a stronger App experience and give you the ability to deliver more relevant content.