The Work Week View is displayed when Calendar is opened the first time. You can change your view at any time from the Calendar toolbar. Changing the Calendar view from the toolbar only changes the view for that session.
The views are as follows:
Day view is one day's activities
Work Week view displays Monday through Friday activities
Week view displays seven days of activities. From the Preferences, Calendar tab, you can select which day is the first day of the week.
Month view displays a month's activities
Schedule view is used when you have more than one calendar. Each calendar is displayed in a separate column.