I spent a bit of time investigating the vCalendar and iCalendar specifications for implementation so hopefully I can help clarify the differences. I'm not an expert on such things, and my understanding is based on my research. I never found an authoritative explanation of the differences. Given that, these are the conclusions that I came to:
1. vCal, iCal, xCal, vCalendar, iCalendar are all different versions of the same specification. 2. Each version of the spec has a different name which is what causes the confusion.
Version 1.0 is called vCalendar (shortened to vCal) http://www.imc.org/pdi/vcaloverview.html - This was developed by Versit.
Version 2.0 is called iCalendar (shortened to iCal) http://www.imc.org/ietf-calendar/index.html - This was developed as IETF standard - It took vCalendar and expanded it. - It was developed in conjunction with iMIP and iTIP (not 100% certain about this) - "If it supports iCalendar, it can do what a vCalendar client does but exchange details about whether a user is free or busy in order to help schedule meetings." -- http://www.imc.org/imc-vcalendar/mail-archive/msg00126.html - If you view the source of an iCalendar event, you'll see vCalendar, version 2.0 listed -- http://www4.macnn.com/macnn/mwny02/jaguar/ical-click5.jpg
Version 3.0(?) is called iCalendar XML (shortened to xCal) http://www.ietf.org/internet-drafts/draft-ietf-calsch-many-xcal-01.txt - Tim Berners-Lee reviewed iCalendar and proposed making changes to the standard to make it xml compliant. -- http://www.w3.org/2000/01/foo - IETF took up the work in a technical workgroup -- http://www.ietf.org/html.charters/calsch-charter.html - This version is still a draft
Applications support iCalendar should support vCalendar events natively. However, I don't believe that applications that support vCalendar (1.0) will support iCalendar events (vCal 2.0). I know of no implementations of version 3.0 of the standard.
As published on July 22nd, 2002. Jason Grigsby, http://wmf.editthispage.com/discuss/msgReader$7900?mode=day