Interesting breakdown. Musically they are pretty different. Phish is much more technically talented but the Dead are more spiritual and relevant lyrically. Still you have 2 bands that play long songs, play shows with different set lists every night, play different versions of many of the songs each time they play them, play lots of covers often better than the originals, improvise albeit in different ways, and because of this have very devoted fans that overlap quite a bit, and a similar scene. I suspect that many of the phans who are bent out of shape by comparisons, never went to a Dead show.