Both of these tablets have different compositions; Shelcal CT tablet contains calcium and vitamin D3/cholecalciferol as active ingredients. Calcium carbonate, Vitamin D3 (cholecalciferol), Folic acid, Methylcobalamin (vitamin B12), Benfotiamine, and Zinc are all found in Rejoice cd3. You should only take the medication that your doctor has prescribed for you based on your diagnosis and medical history.