The main difference between a fracture and a sprain is the magnitude of the injury. In a sprain, the tendons are stretched or torn, whereas, in a fracture, the bones are cracked or broken. Fractures can take a more extended time to heal whereas a sprain, if not that serious, can heal up very early. In comparison to an injury, where you can usually bear weight on your ankles, ankle fractures tend to be very painful.
Most people with a fractured ankle can't put weight on it. A broken ankle or a significant sprain causes immediate swelling, and the ankle cannot be moved. A sprain is classified as a stretched or torn ligament or tendon, while a fracture is a broken bone.