Some people use term Sanatana Dharma and Hinduism interchangeably or consider Sanatana Dharma is synonymous with Hinduism. But it is not.
Hinduism is a collection of customs, dogmas, and superstitions that have coalesced around the sublime teachings of the Vedic sages, while Sanatana Dharma refers to the pool of wisdom that lies beneath the veil of Hinduism.
Sanatana Dharma in this respect refers to the pure wisdom that is based on the direct experience of the sages. Sanatana dharma simply states: Live in conformity with natural laws. Hear and heed the voice of your heart. Do what is best for you and best for others without killing your conscience.
Hinduism, like any other religion, places an emphasis on do’s and don’ts and tries to convince its followers to believe that man-made injunctions passing through the clergy are actually coming from revealed scriptures.
Hinduism is a religion; Sanatana Dharma is a way of life.
Source: Pandit Rajmani Tigunait