The 2020 film The Call of the Wild, directed by Chris Sanders and starring Harrison Ford, stays true to Jack London's novel. The Call of the Wild is a story about a spoiled pet dog named Buck that slowly begins to rediscover its origins and its true nature; Buck answers the call of the wild, as he is stolen and sold as a sled dog and forced to learn how to survive in the harsh conditions of the Yukon—a stark contrast of his previous home in California. This is the main plot of both the book and the film, and all of the events that happen are essentially the same—the film follows the same narrative as the book, which means there are much more similarities than differences between the two.
However, there are still a few important differences that don't necessarily change the plot but are noteworthy to mention.
For example, the novel is much more violent than the film, while the film has a lot more action scenes than the novel. In the film, Buck's first sled masters—Francois and Perrault (who are presented as a man and a woman and a couple in the film, while in the book they are two men)—treat Buck more like a pet, while in the book, they don't hesitate to be harsh and strict with Buck and the other sled dogs.
Buck also isn't as violent with Spitz, the leader of the sled team and Buck's arch enemy, as he is in the book. In the book, Buck injures Spitz very badly and watches as the rest of the dogs tear him apart and kill him, which is how Buck becomes the lead sled dog, while in the film, Buck lets Spitz run away after their fight.
Both in the film and and in the book, Hal—an inexperienced, greedy, and ambitious dog musher—is advised by John not to go to Dawson City, as the ice might crack, which is very dangerous and deadly. Hal doesn't listen to John and takes his sister Mercedes and his brother-in-law Charles and the dogs and heads for Dawson City. In the film, the ice breaks and Hal survives the accident and comes back to yell at John, while the dogs run away; in the book, no one survives, and John and Buck watch as Hal, Mercedes, Charles, and the sled dogs fall into the ice and die.
Finally, the film focuses a lot more on John's character than the book does; John Thornton is basically a main character in the film and even narrates the story, while in the book, he's a secondary character that Buck encounters on his life journey. In the film, John's son (Tim) dies, which is why he decides to move to the Yukon—to wallow in sorrow and sadness, away from everyone. In the book, he goes to the Yukon in the hopes of making more fortune and finding gold. In the film, John is killed in a fire caused by an argument between him and Hal, and Buck arrives too late to save him, while in the novel, he and his friends (Pete and Hans) are killed by the Yeehat Indians; Buck often attacks the tribe to avenge the death of John.