There is a conception that the terms Asura and Rakshasas are interchangeable.
These terms evoke the images of Demons and Evil Doers.
The Rakshasas are said to have been born of Brahma while He was asleep and started eating Brahma.
Brahma started yelling ‘Rakshama’- Protect Me’ and Lord Vishnu banished the Rakshasas from the Earth.
The term Asura indicates ‘Powerful’
There is no other import to it.
P.L. Bhargava says,
“The word, Asura, including its variants, asurya and asura, occurs 88 times in the Rigveda, 71 times in the singular number, four times in the dual, 10 times in the plural, and three times as the first member of a compound. In this, the feminine form, asuryaa, is included twice. The word, asurya, has been used 19 times as an abstract noun, while the abstract form asuratva occurs 24 times, 22 times in each of the 22 times of one hymn and twice in the other two hymns….
Bhargava believes that, in most of the ancient hymns, the word, asura, is always used as an adjective meaning “powerful” or “mighty”. In the Rigveda, two generous kings, as well as some priests, have been described as asuras. One hymn requests a son who is an asura. In nine hymns, Indra is described as asura. Five times, he is said to possess asurya, and once he is said to possess asuratva. Agni has total of 12 asura descriptions, Varuna has 10, Mitra has eight, and Rudra has six. Bhargava gives a count of the word usage for every Vedic deity.”
Citation.
http://en.wikipedia.org/wiki/Asura
