Sri Sri Ravi Shankar: Asuras are those who do not think about the spirit, they are only body bound or Earth bound. The Devas are spirit-bound.
In fact both, the Asuras and Devas are children of the same person. Prajapati had two wives, Aditi and Diti. From Diti, the Asuras came, and from Aditi the Devas came.
That is how the story comes up.