From the general appendices I've looked through, I found the Great Western Ra8lway one to be the most comprehensive.Others will know the precise difference between a cabin and a box. If it helps, other lines used the term cabin, including London Transport. The GWR made matters clearer by putting up nameplates including both the name of the location and a descriptive title such as "Signal Box".
This is one, whuch from memoey, dates from the 1930s onwards.