The 2020 Scrum Guide introduces key updates emphasizing a minimally sufficient framework, the definition of roles within a unified Scrum team, and the importance of product and sprint goals. It clarifies that Scrum teams are cross-functional and self-managing, while also addressing the needs for scaling and the role of the Scrum Master as a leader. Other notable changes include the decoupling of sprint reviews from increments and the formal definition of 'done' for work increments.