"One of the biggest difference between the angels and the devil probably was that the angels voiced out their thoughts while the devil stayed quiet.
The angels did ask ALLAH "Are You really going to create a creature who's gonna spill blood?", but the devil remained quiet; keeping his thoughts and feelings to himself until they became the very birthplace of his biggest mistake that threw him off ALLAH's favour. And ever since, he's trying to get each and every human being to do the same mistake."