The difference is that @chbartist invites people to join his "community" and they are added to the list. This is in his posts:
Feel free if you want to be included in the list of contributors to this community. Just ask at the end of your comment.

So people on that list have asked to be there. This is just spam here, I did nothing to get added to this list and have never had any contact that I'm aware of with this person.