RSS feed: RSS is a web feed format used to publish frequently-updated content. Use this feed in an RSS reader or browser (Safari 2, Firefox 2, or Internet Explorer 7 and higher)
ICS file: Use this feature to download an ICS file to use to import the calendar's event(s) into another program, such as Outlook, iCal, or Google Calendar.
ICS Feed: This is a live feed in the iCalendar format. To use this feed, you will need a program capable of subscrbing to a life iCalendar feed. Some examples include Apple iCal, Microsoft Outlook 2007 or higher, or Windows Calendar in Vista.