I feel that there is no difference between classes and properties.
Every property can be a class.
Every property can be used to create the set of all resoruces that have the property. If the engine needs repair, it's a member of the class of all things that needs something. We uses classes to provide a template for the members. We can use the words 'is' or 'has' in place of 'type'. MyCar is ModelFordEscort.