The difference mainly lies in the way curd and yoghurt is usually prepared. In Indian homes, curd or dahi is made by boiling and cooling the milk and the adding a spoonful of curd to it. The lactic acid bacteria in curd help in fermenting the milk to curd. Yoghurt, on the other hand, is a bit thicker and more homogenous product. In this case, the milk is fermented with the help of certain specific strains of bacteria such as lactobacillus bulgaris and streptococcus thermophilus.