Angels are literal, created spiritual beings, who have significant influence in human life. God created angels in perfection and with choice. Lucifer rebelled against God and led one third of the angels in revolt. Their consequence is eternal torment.
Satan and demons are finite and have the capacity to negatively influence humans. Angels, in contrast, have the capacity to influence human beings toward righteousness. Both angels and humans will enjoy eternal life together, while demons are sentenced to an eternal torment.