-While they both were abandoned, Damien took it much better than Selena. While she dedicates her given life to killing, he dedicates his to saving.
-Damien will go out of his way to ensure children are not harmed, Selena will kill children
-Selena has something green on her head [hair] and red eyes while Damien has something red on his head [horns] and green eyes.
-White sclera vs black sclera
-Selena likes killing and does it actively, Damien hates anyone getting hurt and even gets queasy at the sight of blood
-Blessed by a demon vs is a demon.