With Hotel-X rooms query, you'll be able to get all the rooms for any of your connections. You'll notice that the list of rooms have an object called RoomData in it, which is identical to the one returned in Hotel-X hotels query.
This means the structure of this object is exactly the same in both rooms and hotels queries.
However these will not necessarily share the same data. For example, the data contained in RoomData when you're using the hotels query may have "amenities" , "medias" or "beds" included, but this may not be returned when using the rooms query.
Hotel-X rooms do not composite the data from hotels, it simply takes the data received from the Seller from their corresponding "rooms query" they may have available. Please bear in mind that these are all optional fields (up to each Seller) which may or may not be returned in hotels or rooms queries.