One big difference between opera and theatre is audience behavior.
Audiences at the opera are stone quiet when the music is playing. There's no chit chat or humming. People are concentrating.
During curtain calls or even breaks in the scenes is another story. If you really like the singer or their interpretation of the aria just sung, a well-placed 'bravo' is welcomed. Audience reaction, particularly positive reaction, is audible if not downright noisy.
Also, the audience doesn't stand up and applaud because that is what they're used to doing. Standing ovations are rare. I can't remember seeing one.
On rare occasions, there may be a hearty round of "boos" at the curtain as well.
Opera audiences are more fanatical and generous and critical and discerning and wonderful.
Enjoy.
What is the work you're seeing and where?
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher