As SaucyBoy said, there are two showings of Fantasy in the sky on New Years Eve Eve and New Years Eve. The biggest difference is that the earlier showing (6:30pm) does not include 360° fireworks. Besides that, it’s the same show. Last year, the 6:30pm showing on the 30th had extremely light crowds for a New Years Eve fireworks showing, and that can make the earlier showing more enjoyable to watch. I doubt that Epcot will do two NYE showings, but rather Luminous (the new show that will debut) at 6:30pm and the countdown around 11:50pm. If the show is extremely well received, the countdown might become a tag once again at the end of the show, though.