1. Pressure To Be Perfect.
The pressure to be your best is so much more in theatre. During a performance, you have one shot to get everything right. You have once chance on that stage for every audience to make sure you nail all your lines and blocking, achieve all your character’s objectives and tell the story the best you can. In film, if you forget your lines or blocking or don’t nail everything, you still have another chance. You can always film another take, but you can’t have any re-dos on stage.
2. Live Audience
Performing on stage in front of an audience is addicting. In theatre, you draw energy from the audience and are able to put it into your performance. Actors, especially those in theatre, can tell you that performing in a rehearsal hall is completely different from performing on stage in front of an audience. In film, you usually don’t have a live audience (just depending on the type of show/movie/etc you are shooting), but instead are surrounding by crew members, cameras, microphones, lights, and more.
3. Performance
In theatre, actors have to be “big” on stage. If you don’t project your voice or make every movement or action big and obvious, those sitting in the back of the theatre will not be able to see or hear. In film, you can be more “natural.” You don’t have to project your voice as much or make motions so large. You can show more emotion through your face than your body. You have microphones and closeup camera angles, while you do not get the same luxury in theatre.These three things are the biggest differences between film and theatre. While there are things I prefer about both (such as the live audience in theatre or less pressure to be word-perfect in film), I still love theatre and film for different reasons and will be very happy if I can continue doing both.