Is swelling a hint of wether it is a sprain or fracture? and can it be for both or just one of the two?

Won't hint: Swelling is not a reliable indicator of predicting what kind of pathology might be present. There are other things on exam that are more accurate such as range of motion or lack of it, resisted motions, and specialized test and maneuvers. Best advice is to go see a doctor if there is history of trauma and get some plain x-ray. Stress fractures wont show on xray and might need further imaging.

Can be either: Swelling indicates that there is injury and the healing process has begun. The body's natural splint or cast is the swelling. Whether you need to be evaluated for a fracture depends on how severe the pain and difficulty moving the area are, and if it appears out of alignment or deformed.