ToME: the Tales of Maj'Eyal

Why sometime locations can look different?

I had a character who entered Shaloren camp and it looked like actual camp with green grass and buildings.
Not like dungeon as it is usual.

Another time I had different troll mire, but I discovered locations in different order so decided it was the case.

Most early dungeons have "alternative" variants that occasionally show up. These are things like marshy Trollmire, crystalline Old Forest etc