Asuras and Suras are described in Sanskrit texts as powerful superhuman with good or bad qualities. The good ones are called Adityas and are led by Varuna, while the malevolent ones are called Danavas and are led by Vritra. Devas or Suras are the offspring of Aditi, Mother Goddess whereas Asuras are the offspring of Diti, Sister of Aditi.
Asura is an attribute, a behavior which is full of Rajasic and Tamasic traits. There are no “Sattva” traits in an Asuras but Suras are full of Sattva traits.
Devas, in general, are more benevolent than Asuras. Devas are assigned the territory of Swarga Loka and Asuras are assigned the territory of Paatala Loka. Asuras were more power greedy and attempted to take control of territories beyond Paatala Loka.
Devas often ran to Gods for help and they received help because of their more benevolent nature.