In Harry Potter, there is the Room of Requirement and the Room of Hidden Things; are they both the same ?
The Room of Hidden Things is merely one form that the Room of Requirement can take, for people who have a need for a place to hide something. When Harry goes to find it in Deathly Hallows:
I need the place where everything is hidden, Harry begged of it inside his head, and the door materialized on their third run past.
He’s talking to the Room of Requirement, and when he enters it he finds that it’s taken the form of the Room of Hidden Things.
The Room of Hidden Things is located at the same place where the Room of Requirement is. Although, if the Room of Requirement is being use, the Room of Hidden Things cannot. Only one room may be used at a time. In order to access the Room of Hidden Things, the Room of Requirement must be emptied out, and then it becomes accessible.