Dharma:
Dharma as generally understood, refers to a structured religion or religious duties as mandatory in the scriptures of established monotheistic religions like Islam, Christianity, Buddhism, or Judaism. But in the context of Hinduism or Hindu-dharma, it has a different connotation. The term Dharma can be traced to Sanskrit Dhri-dhatoo which literally means to sustain or hold or which is integral to something, as described by AC Bhaktivadanta Sri Sri Prabhupada. Thus dharma of sugar is to sweeten, dharma of fire is to create heat and burn or dharma of river is to flow or that of air is to blow. As such a human being’s dharma consists of certain duties which make his/her life fruitful. Thus dharma is the unchangeable nature of human beings irrespective of any religious affiliation.

Sanatana-Dharma:
Thousands of years before the term Hindu or Hinduism came into existence, the term ‘Sanatana-dharma’ finds reference in Veda the oldest literature in the world. The duties as mentioned above can be classified into Sanatana-dharma and Varnashrama-dharma. Varnashrama-dharma identifies the economic and social duties of human beings. Sanatana-dharma consists of duties which are typically spiritual in nature. It refers to atman or spirit and thus cannot vary from person to person. Sanatana-dharma is very difficult to define objectively. However the emphasis is on eternal or intrinsic inclination of human beings which is to do service as desired by God and without expecting anything in return. This, according to Rishis is universal and beyond life and death and has nothing to do with one’s belier system. It prescribes the eternal duties that human beings should follow irrespective of birth root. These duties are honesty, purity, non-violence, self-restraint etc.

Hindu-Dharma: The term Hindu does not find mention in ancient literatures like Vedas and Puranas. It has been coined by Persians to mean people living beside the river Sindhu. Basically Hindu means the people living in a particular geographical territory, i.e. Indians living beside Sindhu river. Before Persians gave Indians the name Hindu, the geographical territory was known as Aryavarata. When Greek conqueror Alexander the great invaded this part of the world, Greeks used the term Indu instead of Hindu to denote people living in this territory. This ‘Indu’ later became India and the people came to be known as Indian.

During the period when Muslim rulers ruled India, they levied jazia, a discriminatory tax upon all non-Muslims, thus bracketing all non-Muslims living in India as a distinct religious and cultural denomination called Hindu. Later during 19th century ‘Hindu’ became to be recognised as Hindu religion engulfing the people of India and the Sanatana-dharma.

The root of Hindu-dharma is found in Vedas and Puranas. These books are collection of spiritual laws, discovered by Rishis. These laws are absolute and govern the spiritual world. With passage of time it became a complex tradition encompassing a number of inter-related faiths and practices with common characteristics. The underlying theme of Hindu-dharma is that a human being’s life both present and future is guided by the action or Karma one undertakes. Hindu-dharma is a mystical religion that teaches the practitioners to experience the truth within by way of Karma (action), Bhakti(devotion), and Gyana (wisdom), and feel oneness with God in death.

Hindu-dharma as commonly known is a synthesis of a number of beliefs and traditions, like Vaishnava, Shaiba, Shakta, Shikhism, Jainism etc. Hindu-dharma as practiced today by nearly 1.15 billion people spread over Indian subcontinent, and many parts of Asia consists of certain rituals, festivals, and strict customs. It is the third largest religion in the world after Christianity and Buddhism. Today Hinduism is a political force, synonymous with national identity of India.

Summary: Sanatana-dharma is the oldest religion in the world. It is based upon the collection of spiritual laws discovered by Rishis thousands of years ago. It prescribes certain duties that a human being must perform to achieve fulfilment of life. Sanatana-dharma is pre-historic and absolute in nature. On the other hand the term Hindu or Hindu dharma is a term given by Persians only a few centuries ago, to mean the people living beside the river Sindhu. With the beginning of the 19th century Hindu came to be understood as a collective term to describe the religion practiced by Indians as well as the people of India.