I think they exhibit different ranges of emotion. Phish could always bring across more joy from a songs like YEM and many others, darker places with songs like Bowie and Reba and devil-may-care humour with cuts like Contact while The Dead were masters of melancholic reflection best exhibited in something like Morning Dew and pensieve reflection in a song like Wharf Rat and then strait up longing and loss in something like Sugaree. I dont know if anything can match the deep dark abyss of uncertainty and mystery that tunes like Dark Star and The Other One delved into. All's I know is we're lucky so and so's to have so much music by both these bands to examine and harp on. I just hope Phish doesn't stop writing good songs like The Dead did.