Naturally, there are difference between acting on the stage versus acting for TV or film. Having experience in both is great to make you a well rounded actor. Preparing for these roles are very unique and will differ based on the medium that you are acting for.
The rehearsal time for theatre and film are vastly different. In theatre, you have ample time to bond with your fellow leads as well as take a lot of time with the script, since you will have to have the whole thing memorized for opening night. By the time someone in theatre has opening night they will be very familiar with their part. While acting on the big screen, lines will most likely be changing until the day of or even during filming since things can be edited and scenes are not in order. This environment makes it necessary to get scense down quick so they can move on to the next.
In theatre, the audience is close up and watching your every move. Actors have to make sure that they know their parts well as well as can connect with the audience. Everything will have to be bigger and louder. Facial expressions and emotions will need to be felt all the way to the top row at the theatre. On screen, the camera is most likely 3ft away from you and you are on a much larger screen. Exaggeration will look silly in this environment so everything will have to be subtle and natural and voice will be at a normal level.
In theatre, you are likely playing a character that the audience is familiar with. The characters are iconic, and actors in the theatre have to make sure that they are playing these parts that speak to the characters so the audience is getting what they paid for, as well as putting a new twist on them so that the audience is not bored. On the big screen, actors are playing totally new characters that no one is familiar with. They have been created specifically for this movie and this movie only. There is no reference point for the character which is both good and scary. It is the actor’s job to bring the story to life, and with that the directors are looking for a certain person to fit their vision.
Overall, acting on stage and the big screen are uniquely different. Preparation, audience, character performance, and overall technique needs to be adapted based on the medium. Getting experience for both is great for being a well balanced actor and actress as well as finding out which one you connect with better.