The name Satan or di-a-bo-los in Greek means slanderer because he is the chief and foremost slander and false accuser of God. Satan or Hebrew word sa-tan means resister or opposer or chief Adversary of God.

Satan is the devil's name. The devil is the ruler of hell - opposite to God and heaven. A demon is something evil - in films, demons are often brought in this world with the use of black magic.

"Satan", is "Devil's" proper name "Demon" is a bad spirit, opposite to "angel"

Satan is a character in the bible. The main Christian devil. devils are fallen angels. Demons are parts of the human psyche or subconscious, ones that we'd rather not deal with, but they're still in all of us.