Why do I see two types of Shift Conflicts for a user?

Two main types of Shift Conflicts can be seen when looking at a user's schedule. They can have a Shift Conflict either "Within" or "Across" Opportunities. Both of these Shift Conflicts are when one Shift is occurring on the same date and time as another, with the difference being whether the Shifts in question are within the same Opportunity or across multiple.

2 conflicts