Whereas Kurosawa built Yojimbo as its own thing, a mosaic with pieces and elements from other sources, Sergio Leone’s A Fist Full of Dollars is a straight up copy. It’s a good movie but it’s an inferior remake.
The additions and changes made to the story of Yojimbo are minimal and most are done for two reasons: cultural changes and shortening. The former are obviously necessary to make characters’ action make sense in a new setting. Minor and not harmful to the story. The latter, however…
A Fist Full of Dollars is about 30 minutes shorter than Yojimbo. This isn’t bad in of itself but what is cut out directly affects the character of the Man with No Name. At the same point plotwise, the Man with No Name has been nothing more than a passive observer while in Yojimbo, Sanjuro had already made one attempt to get the gangs to kill each other.
Sanjuro seems to be getting a kick out his attempts at orchestrating a massacre. The Man with No Name has less development and thus his motivations are more ambiguous. Which actually makes him more like the main character from Red Harvest. I really enjoyed that book but I have no idea why the Continental Op acted the way he did.
While there’s room to argue that Yojimbo was an adaptation of Red Harvest, there’s no one to one correspondence between events in the book and events in the movie. It’s more of the over arching plot: man with no name enters town controlled by gangsters and gets them to kill each other. There’s no stand in for Dinah Brand nor murder like that of the newspaper publisher. In A Fist Full of Dollars characters are recognizable copies from Yojimbo. That guy’s Gonji, that guy’s Inosuke, etc. Events are the same down to the Man with No Name escaping in a coffin and and stopping to watch the massacre of one gang with the lid cracked open. The movie honestly doesn’t change enough to be really different. The similarities invite comparison with the original. A Fist Full of Dollars is a good movie, but Yojimbo is better.