is a specific kind of: execution, murder, slaying.

is a broader term that covers: battue, bloodbath, bloodletting, bloodshed.

instances of which are: Alamo | Battle of Little Bighorn, Battle of the Little Bighorn, Custer's Last Stand, Little Bighorn.

derivation: massacre, mow down, slaughter | butcher, slaughter | butcherly, gory, sanguinary, sanguineous, slaughterous.