Is there any difference between saying "back home" and "at home"?
No, there is not much of a difference between "back home" and "at home". Both express the meaning of "at his home". However, "back home" usually indicates that the subject is away from home while "at home" does not always imply this. In this case, however, both can be used interchangeably since they are speaking about him while showing that he is at home. Ex: How is your family back home? Ex: Are you at home right now?