You get the Foggy Lake (Haunted Ship), the Outer Wall (Cornell Only), the Art Tower (Cornell Only), and the Tower or Ruins (Cornell Only).
You get some slight redesigns in the Underground Waterway (Carrie), and the Cave (Reinhardt) but they're very subtle (I think it's just some item placement, textures, and one or two platforms, but I do not have the maps for these so I could be talking out of my ass).
You get bigger redesigns in the Tower of Science, and Tower of Sorcery (Carrie) and the Tower of Duels and Tower of Execution (Reinhardt).
In particular, the Tower of Execution is radically different, as the pillar in the center of the molten steel section isn't completely formed yet, and instead is a smoldering mess of a platform, as opposed to it being a fully-regenerated pillar in the N64 version. I guess the castle hadn't fully configured itself yet.