With direct heat grilling, the food is placed directly above the flame or source of heat. With indirect heat barbecuing, the food is off to the side and almost always under a cover, frequently with added smoke for additional flavor. Direct grilling is rapid cooking at a high temperature, while indirect barbecuing is much slower at a low temperature.
The barbecue chef's motto: "Low and slow is the way to go."
For example, in a typical home grill with two separately controlled burners, grilled foods are placed over both burners, while if barbecuing, one burner is turned off and the food is placed over the cold burner and heated from the side. The meat is turned several times to ensure complete cooking.
This method of cooking breaks down the collagen in meat and turns tougher cuts into easy eating.
Barbacoa comes originally from Nahuatl and it made its way into Spanish. Traditional barbacoa implies digging a hole in the ground putting some meat (goat is the best, usually the whole animal) on it with a pot underneath (to catch the concentrated juices, it makes a hearty broth), cover all with maguey (cactus) leaves then cover with coal and set it in fire. A few hours later it is ready.
Barbecue is traditional food in the Southern United States with many different regional variations. Typically meat is covered with barbecue sauce which can be tomato or vinegar based. Vinegar-base sauce is typical of Southern barbecue while tomato-based sauce is Western style.
Barbecue styles vary across the Southern US. For instance, Texas style barbecue involves more beef than pork (which is used more in the Eastern U.S.) Texas style barbecue involves cooking over mesquite wood smoke, which gives the meat a red tinge even when fully cooked. Texas barbecue is often not covered in barbecue sauce when it is served, but instead the sauce is applied while cooking on the grill, where it slowly soaks in. In Texas barbecue is traditionally served with "spanish" rice, pinto beans and potato salad.