When this feature is enabled, sounds are silenced, so the Apple Watch won't interrupt music or someone that's speaking. The screen operation is also affected, staying dark even on Apple Watch models that support an always-on display. Lift to wake is disabled in this mode and a tap is required to activate the screen.
What does theater mode do on Apple Watch?
Use theater mode on Apple Watch
Theater mode prevents the Apple Watch display from turning on when you raise your wrist, so it stays dark. It also turns on silent mode and makes your Walkie-Talkie status unavailable, but you still receive haptic notifications.
What is the difference between theater mode and do not disturb?
“Theater mode” puts your phone into silent mode and also turns off the display, unless you tap it or press a button. Your watch won't ping or light up, but it will vibrate. Turn this mode on and off by tapping the comedy / tragedy icon. “Do Not Disturb” turns off the haptics, too.