noun
inside a room; interior of a room
General term for the inside of any room. Often used in descriptive or formal contexts.
房中には誰もいなかった。
There was no one inside the room.
noun
inside a bedroom; interior of a bedchamber
Specifically refers to the interior of a bedroom or private chamber. Less common in modern everyday speech; often appears in literary or historical contexts.
彼は房中で静かに本を読んでいた。
He was quietly reading a book inside his bedroom.