The thing with film and theater is that you always know the story so you can play certain cues in each scene with the knowledge that you know where the story's going to end and how it's going to go. But on television nobody knows what's going to happen, even the writers.
When you work with a good actor, there is this natural rapport and chemistry that develops over time. That chemistry helps your characters come alive and makes the story of the film that much more convincing.