In the true story of 'Revenant', the real - life events were probably more mundane in some aspects compared to the movie. The movie likely enhanced the action scenes. For example, the bear attack in the movie was made more dramatic. Also, the relationships between characters in the movie might be more fictionalized. The real Hugh Glass's story was more about survival in its rawest form, while the movie had to add elements to appeal to a wider audience, like some sub - plots that may not have been part of the true story.
One key difference is the amount of time. In the true story, Hugh Glass's journey took a long time which might be compressed in the movie. Also, the movie might have added some fictional characters for dramatic effect that didn't exist in the real story.