What fundamental differences and similarities exist between theater and film acting? Under what conditions do actors perform in each medium? This study explores these questions with the aim of explaining the challenges and problems faced by theater actors who wish to transition to film. The examination of acting in theater and film reveals that there are different theories and acting teaching methods that can assist actors in dealing with their roles. This work specifically addresses the hypotheses and methods of Konstantin Stanislavski and Lee Strasberg, contrasting them with Bertolt Brecht's theory of the new acting art. The focus is on the actor, the realization of their role, and the associated ambivalence.