Comparison Nightmare Alley (2021) vs Nightmare Alley (1947)

I saw Guillermo Del Toro's 2021 version first, without knowing that it was a remake based on an earlier novel, which I have not read. I had seen a teaser trailer in a theater, and the spooky lighting made me think it would be another surreal Del Toro fantasy story. It is actually based on a pulp novel that was made into a noir film.

2021 is 40 minutes longer: 2 hours 19 minutes vs 1947's 1 hour 10 minutes. 1947 was too rushed. You did not get to know the characters. Too much is left out. 2021 has a much stronger emotional impact and tells the story better. They could not have told this story this way in 1947. In fact, the studio bought the rights to the novel without anyone having read anything more than a book review. When they read the novel, they realized that it was too dark and violent for a 1947 black and white film.

Del Toro said in an interview that he did not want to remake the 1947 film, but to adapt the novel, which was a reflection of the author's life. 2021 has better acting from a stellar cast, better lighting and sets.

Rooney Mara fills out the two-piece carnival costume better than her 1947 counterpart. Her character's story is better than the 1947 film. David Strathairn has more screen time and performs better than his 1947 counterpart. The 1947 studio insisted on adding an uplifting scene at the very end, that was not in the novel. The 2021 ending is truer to the story, to the novel and to the characters.

After seeing both films, a good analysis:
Nightmare Alley: 10 Biggest Differences Between The Del Toro Movie And The 1947 Version
https://screenrant.com/nightmare-alley-biggest-differences-between-remake-original-movie/