General Indigestion is a typically caused by eating too quickly, especially when the food is high in fat. Indigestion can be felt as a burning sensation in the upper portion of the stomach, general nausea, bloated, heartburn, and among others a bitter taste can result in the month from stomach acid that is coming up into the esophagus. The most commong way to relieve indigestion is to take indigestion tablets, that battle to neutralize the extra acid, so that the indigestion can be eliminated.
Acid indigestion on the other hand, is similar to 'general indigestion' above, however it involves an excess of hydrochloric acid in the stomach. if Acid indigestion is experienced frequently it can wear on the duodenum and the lining of the stomach, both which are aggravating and can lead to conditions such as ulcers, which can be life threatening. It is important to know that acid indigestion is different from heartburn, which is the aggravation more specifically of the esophagus.
Acid indigestion is most commonly attributed to eating foods that have too much fat in them, but can also be do to too much spice, or an excess intake of caffeine or alcohol, smoking, overeating, or simply just eating too late in the evening(like right before going to bed).
Antacids can help to relieve the problem short term, however, it is known that a dependence can develop on these over the counter remedies, and isn't recommended as a long term solution. Be smart with your dietrary habits as your life is depending on you!