Webinar can be used as a backup Gotomeeting too -- which is nice. When you create the webinars they are listed online so we could see who has a session scheduled.
Citrix has several variations of GotoMeeting that they label differently (GotoMeeting, GotoWebinar, GotoTraining) - they all seem to do pretty much the same thing with slightly different options (# of concurrent users, ability to have the Goto system manage sign ups, ability to give participants some type of quiz/test).