The show is the same even during the Christmas season. They don't do a Christmas show (or at least they haven't in the past but anything can change). There is a meet and greet both before and after shows. Check your park map when you arrive for the times of the shows and also the meet and greets. There is a great interactive Barney play area when you exit.
http://www.universalorlando.com/the.../attractions/woody-woodpeckers-kids-zone.html