What is the main difference between a sprained thumb and a broken thumb?

Hard vs Soft Tissue!: A fracture involves hard tissue - i.e. Bones. A strain, or sprain involves soft tissues - muscles, ligaments, tendons, or cartilages. A fracture is often treated by immobilzation in a splint or a cast. Soft tissue injuries usually respond to cold compresses initially, and then changing to warm compresses and movement therapies. Xrays and bone scans for bones. Mris for bones and soft tissues.

Sprain vs Fracture: We are talking about apples and oranges. A fracture equals a broken bone. A sprain involves a ligament injury. Ligaments are between bones and help with stability. Fractures are either displaced or nondisplaced. Ligaments can be stretched, partially torn or completely torn: gr. 1, 2 and 3 respectively. Both a sprained thumb and a broken thumb may need to be immoblized.

The injury: A sprain refers to a tear of a ligament and a broken thumb refers to a fracture or break of the bone.