deities and the divine
What is the difference between a deva and an asura in Hindu tradition?
How the words started out
In the earliest hymns of the Rig Veda, the word asura did not mean demon. It meant something closer to mighty lord or one with power. It was used for great and powerful beings, including some who were later called devas. Over time the two words pulled apart. Asura came to mean something opposed to the devas, and the split hardened in later texts. So the sharp good-versus-evil divide is not as old as the words themselves.
What the tradition says
By the time of the Puranas, the picture is clearer. Devas and asuras are both powerful beings, both born from the same divine source in many stories. They are not entirely unlike each other. What separates them is their nature and their aims. Devas are linked to light, order, and the sustaining of the world. Asuras are linked to pride, desire, and the disruption of that order. Many Puranic stories show asuras who are deeply devoted, learned, and even beloved by the gods, yet still caught in their own ego and hunger for power. The Bhagavata Purana speaks of daivi sampat and asuri sampat, divine qualities and demonic qualities. The divine side includes fearlessness, honesty, compassion, and self-control. The other side includes arrogance, cruelty, and seeing the world as existing only for oneself. These are presented as tendencies, not fixed races.
A battle inside as well as outside
Many teachers read the deva-asura conflict as something that happens within every person, not only in the heavens. In this reading, the devas represent qualities rooted in sattva, a quality of clarity and balance. The asuras represent forces rooted in tamas, heaviness and self-serving darkness. The great cosmic battles in the epics and Puranas can then be read as a picture of the inner struggle between these tendencies. This is one interpretation, not the only one, and it sits alongside the more literal reading where devas and asuras are real beings in a real cosmos.
Are asuras simply demons?
Calling asuras demons is a rough translation. It carries ideas from other traditions that do not quite fit. Some asuras in Hindu stories are complex figures, not simply evil. Prahlada, born among the asuras, is celebrated as one of the greatest devotees. Mahabali is remembered with love and honour in Kerala. The tradition holds that what matters is a being's qualities and actions, not the group they belong to. So the deva-asura difference is real in the tradition, but it is not a clean line between the wholly good and the wholly wicked.