What is the difference between a metabolic acidosis and respiratory acidosis?

Resp = CO2 retention: Respiratory acidosis relates to co2 retention, otherwise known as "hypercapnea". Metabolic acidosis occurs either from primary acid retention, renal dysfunction/failure or bicarbonate (sodium bicarbonate) losses. Primary acid retentions cause anion-gap metabolic acidosis from these etiologies (methanol, uremia, diabetic ketoacidosis, para-aldehyde, isoniazid, lactic acidosis, ethylene glycol, salicylates).

Acidosis: There are two types of metabolic acidosis. One is seen with a very low carbon dioxide and one is seen with a high chloride. The first one is due to the presence of an acid in one's blood. Examples of this are a lactic acidosis or diabetic keotacidosis. The second type is seen in a loss of bicarbonate (sodium bicarbonate). In both the serum co2 is low. A respiratory acidosis has a co2 that is high.