In brief: only the name remains the same.
D002119:Calcium Carbonate / Q000737:chemistry / Q000145:classification; D019355:Calcium Citrate / Q000737:chemistry / Q000145:classification; D002626:Chemistry, Pharmaceutical; D006801:Humans; D009275:Names; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000145:classification*
D004364:Pharmaceutical Preparations; D002119:Calcium Carbonate; D019355:Calcium Citrate