An entity is a basic object managing properties and various components that can be attached dynamically. The set of components can other set up information for entities (like base script file etc) can be configured (entity configuration).
Entity configurations allow us to use different set ups for the same type of entity, either in a single simulation or, for example, in a networked application.
For example, in a client/server application with the server being a dedicated one (i.e. no graphical rendering needed) it may be desirable to omit the “visual” component(s).
Furthermore this makes it possible to customize the behaviour on clients vs servers and allows for code seperation of client and server code.
And it makes it possible to reuse components (within reason).