B.A.Nana, it does differ from TTV in that it is more of a “movie”. AFAIK (Danny Boyle is interviewed on Mayo and Kermode’s film review; it should still be available as a podcast or listen-again), it is true to the actual incidents. While TTV relied on both the drama and interviews with Simpson & Yates for the narrative, 127 Hours relies purely on effects and direction from Boyle for it’s narrative. There is no vocal input from Ralston during the film.
But, as I’m sure you know, Boyle doesn’t mess about with stories. Obviously he needs to translate Ralston’s experiences into visual effects but IMO, he does it very well.
FWIW, I think TTV is a better film. As a European, I think we connect more with the modest understatement of Yates and Simpson whereas Ralston does come across as a slightly annoying adrenaline junkie at the beginning of the film. This annoyance wears off though.