This comprehensive comparison is made possible with the collaboration with Mr. Alex Tan Yun-Kai of Malaysia, a huge Mi Fan indeed.
We don’t really recommend you flashing the Android Q Beta yet to your Mi 9 as it still has plenty of bugs to be fixed, nevertheless we made this comparison for Mi Fans to enjoy and see the improvements from Android Pie to Android Q.
1. Dark Theme
One of the most requested feature, the dark theme is now available in Android Q, that’s for sure.
You can select from the Theme, light or dark 
Its hidden in Display
Its also in the drop down menu 
2. Full Screen Gesture
This one is pretty much new to Android Q, Android P can only support 2 button gestures but Android Q improved it further to better support the new breed of smartphones
The only gesture selection for Android P 
The biggest improvement on Android Q
3. Time to Read
This on is how long the message will be displayed before it will automatically exit, not all apps will support this mode.
4. Share WiFi via QR Code
This new feature is useful when you don’t want to tell your friend your WiFi password at home, instead you just ask him to scan your QR Code to keep you safe from them possibly sharing your passwords to other people.
Android P doesnt support QR Code
Now you can share your WiFi without sharing your password
5. Interruptive or Gentle Notifications
This new feature enables your to get the more important apps to notify you using tones and vibrate and banners, while the not so important apps will notify you but will not vibrate nor appear on the lockscreen and banners.
Android Q 
Android Q
6. File Manager
The change in file manager takes a big step, in Android P we can see that it only shows the downloads folder, while on Android Q it shows you the recent photos and screenshots. Then you can categorize it into Photos, Videos, Documents on the tabs on top.
Android P 
Android Q
7. Unlock Screen
The unlock screen we can see that in Android Q, they removed the Time as well as the Enter Icon has also changed.
Android Q 
Android P
8. Themes
Now you can customize the color of your theme with preset colors, the font change as well as the icon shape change.
Theme Color Setting 
Font Setting 
Icon Change Settings
9. App Installation Screen
The Android Q takes a more minimalist approach in installing app screen.
Android Q 
Android P
10. Emergency Contact
Both Android P and Q has the emergency contact on the lock screen, but the Android Q added another way of accessing the Emergency Button, by long press on the power button, you can access the emergency contact there.
Android P
Android Q 
11. Volume interface changed
The volume interface also took a little minimalist design change.
There are some limitations or bug that we were able to see in the Android Q inside the Mi 9
1. The camera app is too simple, everything is absent like the ultra wide angle, the HDR, AI, Beautify.
2. Camera2API is enabled, but cannot install G-Cam
3. Smart Parenting not available
4. Smart Reply not available.
We have gathered the AnTuTu Rating of Mi 9 running Android Q.
It was really a nice experience to able to play with the Android Q Beta inside the Mi 9, we can say it did improved over Android P, but there are many aspect that they need to fix before launching this to public.
What are you expectations on Android Q, pop your suggestions below.