The Home interface is used to create the EJB Object and pass this reference to the client (caller).
The Component interface is used to define the business logic (methods) that are provided by the EJB that linked up with the EJB Object.
Can you imagine that, the EJB object creates itself from non-existing, and then send itself to you as the reference, and provide you the services?
10x Nick for detailing a little bit my thoughts (time was pressing me :-) ).