The main differences between adenosylcobalamin and methylcobalamin are different structures, different actions, and different degrees of rapidity of absorption. 1. Structural differences: adenosylcobalamin has deoxyribose adenosine connected to the center cobalt atom. In methylcobalamin, the methyl group is connected to the central cobalt atom. 2. Different functions: the main function of adenosylcobalamin is to treat megaloblastic anemia, dystrophic anemia and anemia in pregnancy. Methylcobalamin is mainly used to treat megaloblastic anemia and peripheral neuropathy. 3. Different degree of absorption: In absorption, the absorption speed of methylcobalamin is higher than that of adenosylcobalamin. So there is a difference between these two drugs, and it is recommended to follow your doctor’s advice before choosing a drug.