What constitutes a venial sin?
Correspondingly, what is considered a venial sin?
Venial sins are any sins that meet one or two of the conditions needed for a mortal sin but do not fulfill all three at the same time, or they're minor violations of the moral law, such as giving an obscene gesture to another driver while in traffic.
Considering this, what is the difference between a mortal sin and a venial sin?
Mortal sins are contrasted with venial sins, which usually involve a less serious action and are committed with less self-awareness of wrongdoing. While a venial sin weakens the sinner's union with God, it is not a deliberate turning away from him and so does not wholly block the inflow of sanctifying grace.
3), a venial sin is a disposition toward a mortal sin. Therefore, a venial sin can become a mortal sin. But contrary to this: Things that are infinitely different from one another are not transformed into one another.