well yea there's the obvious "Entrance" part, but not sure if there is a more specific name to that type of section of a castle. Then there's the library, another important one.
well stuff like an Outerwall, that really doesn't count as it's own sector. But stuff like Marble Gallery is kind of tough to describe. I don't think every castle needs a colloseum though. Well yeah there is the underground, even though that is technically not a part of the castle.
and of course the Keep, but that's pretty obvious. Clock Towers always make castles better.
But overall, it's really tough to describe and lable sections of a castle, because some of the areas share a theme of walls, pillars and stairs. One of the castles
even had a theater built in. Oh yeah, I think the Courtyard is a popular location in a castle. then there's what could be called the dungeon. but I think in one of them, some of those were located in the upper levels, not necessarily the basement.