The asura is one who is striving for success. The deva is one who is, or has been, successful. A determination to be successful drives the asura to do tapasya. Fear of losing what they have or fear of never getting back what they lost makes the devas seek Brahma. The asura does not believe that anyone will help him. The deva believes that God exists only to help him while he does not exist to help anyone. In other words, the asura does not believe in atma whereas the deva believes in param-atma, but has yet to realize jiva-atma, the human potential.
