you use bruh to express your disappointment and bro to address someone
WHAT IS THE BEST GAME IN THE WORD

I guess this pretty much says it all - from the urban dictionary:
Bruh -
The reaction to every single situation possible. The most versatile word in existence. Can be used to show happiness, sadness, distress, anger, fear, sleepiness, disgust, approval, disapproval, confusion.. and many more!
And what's the difference between "Bro" and "Bruh"? lol