Site Structure is how your site is laid out.
In Jomres, individual hotels, B&Bs, Villas, Gites etc are all referred to as Properties ( or Busnesses ).
You can have different Business types, such as Hotel, Cottage. Each business ( property ) can have different features. These features ( which can be assigned to multiple property types ) can belong to a Business Feature category.
Just like in real life, a business (e.g. hotel ) offers resources ( e.g. rooms or berths ) for rent. Here you create the different resource types, you can also create global resource features. Resource features can be used in the booking form to filter rooms for example, allowing guests to specifically choose only rooms with a balcony. Property managers can add their own resources ( room ) features in the frontend, but those features are specific to just that property.