If shaving the beard is one of the major sins, how can one differentiate between major and minor sins that are expiated by prayer and fasting, and what are examples of each?

Shaving the beard is haram (forbidden), and it is a minor sin. However, persistence and regularity in shaving the beard, as is the case for many who shave it, transforms this minor sin into a major one, because persistence in minor sins and openly committing them makes them major sins.