"Grilling and barbecuing are two different things," says Naz Cavallaro, grilling expert with Weber-Stephen Products.
Grilling: Takes less than 20 minutes of cooking time; flavour comes mainly from the caramelization of the meat. It doesn't have to be done on a barbecue; you can "grill" in a cast-iron pan.
Barbecuing: Takes more than 20 minutes; flavour comes mainly as a result of drippings hitting a heat medium like charcoal or flavourizer bar and vaporizing to create white smoke that goes into your food and gives it a barbecue flavour.
For perfect cross-hatch grill marks: Put steak on very hot grill at 10 o'clock position. For a 2.5-cm (one-inch) steak, leave about 1 1/2 minutes, then move a quarter-turn to the 2 o'clock position with same side down. After another 1 1/2 minutes, flip steak over, but still in 2 o'clock position. After 1 1/2 minutes, turn back a quarter-turn to 10 o'clock position. Leave another 1 1/2 minutes. At this point the steak will be close to medium-rare and can be removed from the grill. If more cooking is required, move to the other side of the grill where the burners are on low or off.
NEVER cook with the lid open (even for the brief 1 1/2 minutes of making the cross-hatch marks). "If you're looking, you're not cooking," Cavallaro says.
Source: Grilling expert Naz Cavallaro of Weber-Stephens Products.