If you removed the wall and floor textures and music, of course you couldn't tell them apart. I couldn't tell you the difference in dungeons in say....Grandia II or any other RPG for that matter if you remove all the elements that make said dungeon unique.
It's pretty bad that the only elements that make Persona 4 dungeons unique, even from each other, are textures. Meanwhile, you could remove the textures from all of the dungeons in Final Fantasy XII (I haven't played Grandia II so I'm not going to use that as an example) and they'd still be distinct from each other.
When I think of Raithwall's Tomb in FFXII, I think "That's the one that's bilinearliarily symmetrical, with two wall bosses, the second of which is optional but will open a secret passage when you defeat it, causing the floors on either side to collapse into staircases that take you to a chest with a powerful weapon in it. And there are three teleporters in the middle, two of which send you to centers of the mazes on the east and west sides, and the middle teleporter takes you to the basement, where there's a giant square stairway leading to the lowest level and another boss fight." And none of those things have anything to do with how the walls look.
Now, when I say "The dungeon with the corridors that sometimes branch off into square rooms that have chests or enemies or stairs in them," which Persona dungeon am I talking about? And if I describe one as "The one where you have to get a key, go down two floors to unlock a door and get another key, and go back up to use the key to unlock another door," how interesting does that sound?