Both “Business Days” and “Weekdays” are set to be Monday through Friday, excluding weekends. Business days will also exclude holidays and will automatically roll the due date of the task forward to the next available business day if a holiday occurs. “Weekdays” also excludes weekends but will include holidays and gives you the option to either roll forward OR roll backward a day when a holiday occurs. While, the “Days” option means all days of the week are open, Monday through Sunday - including weekends and holidays.