Demons are evil spirits, and a source or agent of evil, harm, distress and ruin.
Supernatural beings of Greek mythology intermediate between gods and men are demons.
The Devil is the supreme spirit of evil, believed by worshippers to be the tempter
of mankind, the leader of all apostate angels, and the ruler of Hell.
Satan is devious, behaves devilishly, and performs blatantly mean and evil acts of devilment.