Hey beamer, is Christmas nights just a demo? As opposed to straight up Nights?
Its just one level that you can play with both characters, but its still pretty fun. Each time you win you get some chances to win "presents" which are little extra goodies that range from picture galleries, to special modes, to karaoke videos lol. Its pretty neat I think. Just good for getting in the Christmas spirit

Its sensitive to the date, so if its near Christmas time it does a Christmas theme, if its New Years, it has a different theme. If its January or something, it comes up as Winter Nights... there might be some others that are date dependent (april fools maybe??) I havent tried manually changing to other dates though.