The word Hindu is a combination of the first letter “Hi” of Himalayas and the last compound letter “ndu” of the word Bindu. It refers to India as Hindustan, a country between the Himalayan Mountains and Bindu Sarovaer (cape Commorin Sea). Sanatan Dharm is the correct name for Hinduism. Sanatan Dharm means eternal Dharm. So there is no difference. Throughout time and social changes the word Hindu became more popular to define Sanatan Dharm.