Cholecalciferol, (sometimes called calciol) is an inactive, unhydroxylated form of vitamin D3)Calcifediol(also called calcidiol, hydroxycholecalciferol, 25-hydroxyvitamin D3, etc. and abbreviated 25(OH)D is one of the forms measured in the blood to assess vitamin D statusCalcitriol(also called 1,25-dihydroxyvitamin D3) is the active form of D3.