Chapter 9 is similar to Chapter 11, except it is used by a municipality, and therefore not relevant to the individual debtor.
Chapter 11 is probably the most well known type of bankruptcy. Corporations and individuals that don't qualify for a Chapter 13 Bankruptcy because of being over the debt limits can file this type of bankruptcy. Chapter 11 Bankruptcy allows a corporation the chance to reorganize and stay in business or for the individual to keep his or her assets.
Chapter 12 is used by small farmers and fishermen with regular annual income. This type of bankruptcy is similar to Chapter 13 Bankruptcy.
Chapter 15 Bankruptcy is the newest type of bankruptcy. It is used when a bankruptcy involves matters outside of the United States.