What are the key differences between general relativity and Newtonian gravity in terms of their explanations of the behavior of massive objects in the universe?

General relativity and Newtonian gravity differ in their explanations of the behavior of massive objects in the universe primarily in terms of the concept of space-time. Newtonian gravity describes gravity as a force acting between two objects, while general relativity views gravity as the curvature of space-time caused by the presence of mass. This leads to differences in predictions, such as the bending of light around massive objects and the existence of black holes, which are better explained by general relativity.