The big change for compact mode is that the sidebar collapses down into icons, meaning that the sidebar takes up less real estate.
The Xbox PC app will also now only show unread notifications when you look at the notification drop-down and is getting a "Gaming Services Repair Tool" to help you troubleshoot issues. There are a few improvements for Xbox consoles, too, including the ability to pick a specific Japanese keyboard layout.
[
add
]
[
|
|
...
]