One is the story of the model; how it was dreamed, planned, constructed and developed. It tends to practicality and compromise, it has limitations and shortcomings.
The other is the story told by the model, where the engines are full size and the figures have lives of their own. It can be ambitious, whimsical, impractical and quite irresponsibly inconsistent.
Here are the stories of the Cwm Clogwyn Railway.