What is the difference between a venial sin and a mortal sin?

Venial sins are minor offenses such as lying or cheating. examples of absolution may include praying the rosary. A mortal sin is a grave offense, such as murder. Both types of sin require one to go to confession and ask the priest for absolution. Absolution is necessary so that If you died, for example an untimely death, one's sin/s would be "washed" from your soul and offer entrance into heaven.