This seems to fit right in with this discussion. It is a quote from one of my cookbooks, "How to Grill" by Steven Raichlen. It is part of the intro to the book.
"The word barbecue means different things to different people, depending on where you live. On the East and West Coasts of the United States and in the Frost Belt and Canada, it describes any sort of live-fire cooking outdoors. In Texas, the South, and parts of the Midwest, it refers to a specific kind of meat that's slow cooked and heavily smoked, usually via the indirect method. Thus, to a North Carolinian, barbecue means pulled pork; to a Texan, beef brisket. Elsewhere, barbecue may refer to a piece of cooking equipment (the barbecue grill), a social gathering (for example, a church barbecue), or simply a meal outdoors."
Until I started getting into the subject, grilling and barbecue were interchangeable terms. For most of people I've known where I've lived (Minnesota, Montana, and Colorado), they still are. In these regions, only the purist makes a distinction. You can do barbecue fast (grilling), or slow (barbecue or smoking), but it's still covered under one generic term.
Sort of like my grandmother always called all cameras "Kodaks", regardless of the actual manufacturer. It's one of those terms that has taken on a colloquial meaning that varies greatly from region to region.