In this instance BBQ is referring to a specific type of food - that is, smoked meats, usually beef or pork, which is then covered with barbecue sauce, which is

In this instance BBQ is referring to a specific type of food - that is, smoked meats, usually beef or pork, which is then covered with barbecue sauce, which is usually tomato-based. The specific meats, rubs, and especially sauces vary from place to place, and this is what people are referring to when they debate which state or region has better BBQ. A barbecue could refer to an outdoor grill, but I don't think that's too common in the US. More often, it refers to a party held outdoors in which food is grilled, usually burgers and/or hot dogs.