Navigation & Interface
Both Yahoo and Google Calender have two panes; the left pane has a small monthly calendar with highlighted dates that have events attached to them. The second pane takes maximum space with a big calendar, where you can add your events/tasks.
Google Calendar – Google Calendar has tabs that allow user to view events linked with a day, week or month. The default allows the user to see the events of the next four days (User can change the time range).
To add/edit an event, you need to click on the date, month and time. A popup appears that allows you to enter your text. Since Google uses AJAX call, saving an event is very quick, as it does not involve page reload.
Google calendar has keyboard shortcuts to create an event or search an event. This feature is not available in Yahoo Calendar.
Yahoo Calendar – Unlike Google, Yahoo allows you to set priorities, the option to set completed task, track events, and allows personalization (add colors and calendar Photos to events).
To add an event, you need to click on the desired time or on 'add link' option, and enter the necessary text. Keyboard shortcuts are not available in Yahoo Calendar. All the functions must be performed with the mouse.