Exotoxins are toxins that are produced by bacteria. The bacterial cells secrete them as a defense mechanism. They are potentially dangerous to humans but the human immune system can counteract them with antibodies. They can also be counteracted by heat. Enterotoxins are a type of exotoxin. They specifically target the intestines which are also referred to as the entrails (hence the name enterotoxin). They damage the intestines by altering the permeability of the intestinal membrane. So enterotoxins are a specific type of exotoxin. Neither of these should be confused with endotoxins, or other bacterial toxins that are not actively secreted by the bacteria but are released only when the bacterial cells are ruptured.