VITAMIN D NOMENCLATURE:

1. Cholecalciferol = Vit D3 = Calciol
2. Ergocalciferol = Vit D2

3. 25-hydroxycholecalciferol = Calcidiol

4. 1,25 dihydroxycholecalciferol = Calcitriol

Animal sources have Cholecalciferol
= Vit D3=Calciol

Plant sources have Ergocalciferol = Vit D2
MC source of Vit D = SUNLIGHT...

UV B causes Photoconversion of 7-dehydrocholesterol in the Stratum basale & spinosum into Cholecalciferol=Vit D3=Calciol