Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are both forms of fatty liver disease. NAFLD is the buildup of fat within the liver. However, with this variation, no damage is present. NASH is a type of non-alcoholic fatty liver disease that also involves the buildup of fat in the liver, yet, in this case, inflammation, damage, and even scarring have developed.