The Home Counties are the ones that comprise (what we Americans would call) the greater London metropolitan area. There is no precise definition of the term, and there is not even agreement on which counties, or how many, make up the list.(I live in New York). I recently became aware of the idea of "home counties" in England (London suburbs). How did the name "home" (which seems to have a long history) come to describe this region.
There is not really any such thing as the "greater London metropolitan area". There is "Greater London" and there is the "London metropolitan area", which is also known as the "London commuter belt", which is forever growing due to improved transport links.The Home Counties are the ones that comprise (what we Americans would call) the greater London metropolitan area. There is no precise definition of the term, and there is not even agreement on which counties, or how many, make up the list.