There are various categories of skeletal fractures :
Closed (or simple) fractures: The skin remains intact, and the surrounding tissue, nerves, arteries, are unharmed. It may be difficult to treat, as you need to see a specialist who can make sure the bone didn't cause internal injury. Heals the fastest and with least aftereffects.
Open or compound fractures: The bone protrudes from the skin through an open cut. There is a risk of infection, and takes longer to heal.
Complicated Fractures: Major surrounding areas and tissues are damaged near the break, such as nerves, arteries and veins, and organs, such as Pneumothorax. Happens frequently in car accidents and high velocity force. Delayed healing or 'union' of the break, or sometimes permanent nonunion.