They often have a strong emotional core. Since they are based on real people's experiences, there's usually a lot of real - life drama and emotions involved. Take 'The Blind Side' for instance. The story of Michael Oher's journey from a homeless boy to a successful football player is full of heart - warming and inspiring emotions.
They might use real - life footage or interviews if available. Some documentaries or docudramas that fall based on true story will incorporate actual footage from the events or interviews with the people involved. This adds an extra layer of authenticity to the story.
Accuracy in key events. For example, if it's a historical event - based movie, they usually try to get the dates, locations and main actions right. Like in 'Apollo 13', the movie accurately showed the sequence of problems that occurred during the space mission.