You, like many Americans, fail to distinguish between Barbecuing and grilling. Some Americans think that slapping some barbecue sauce over the meat makes it barbecued; that is incorrect. Except in Australia, barbecuing includes not only sauce, it also means long slow cooking over low heat (if you cooked it for less than three hours, then you didn’t barbecue it). Grilling is just the opposite: fast cooking over high heat, e.g. the backyard grill. In Australia, due to their imperfect understanding of the English language, they call a backyard grill a barbie. (I have no idea of what they call the doll.)
And the entire American south from Texas to the Carolinas.
I can only assume you are referring to Cecil’s column Does barbecuing cause cancer?
I, too, was dismayed at Cecil’s misuse of the terms barbecuing and grilling, i.e., using them interchangeably when they are two quite different things altogether.
I use them interchangeably, like vagina and vulva.
Language changes over time. Being a fan and practitioner of both cooking styles I’m a bit uncomfortable with the lack of distinction but we’re just going to have to get used to it.
Never!
So are these regionalisms in the U.S., or are some people just wrong?
Growing up in L.A. (1970s), we used the Australian sense of “throwing things on the BBQ” when we grilled, while being well aware that a Kansas or Texas or wherever style BBQ was something quite different.
Edit: “Grill”, on the other hand, was used exclusively for putting it close to the flame in an inside oven, on the grill setting. Synonym with “broil”.
This is an extremely common usage of the words. As with pretty much all words Barbecue has a variety of meanings. Sometimes it means cooking over direct heat as is used in the column. A quick survey of dictionaries puts this meaning as the most popular.
Your very arbitrary time of “less than three hours” is hogwash. Yes, I want my whole hog pork in Eastern NC cooked over coals overnight. No sauce necessary(maybe a mop sauce of vinegar/reed pepper flakes). But I could barbecue a bluefish over smoke and low heat in just under three hours.
Heathen!
I know. I can’t believe he eats that stuff.
FWIW, it’s always been “grilling” and “the grill” to me (Northern CA and those I know here in the northeast.) But the terms are largely synonymous in my mind even though I know the different origins and “core” of each cooking method.
I rarely “barbecue.” But I have a neighbor who has never turned his grill up past about 300, either. 
I was corrected here about that some years ago and now I don’t make that mistake anymore. I grill very often but I have never barbecued.
Pssh! You think that’s bad? Have you seen what they call tigers?
It’s only a certain American subculture that somehow morphed the meaning of barbecue into something very specific.
The word comes from Caribbean natives for a gridwork of sticks used to cook over a fire. (And similar structures for sleeping, storage, etc.)
It’s still used in that general sense all over America and the world.
I have no idea where the notion of a specific way of grilling (and often not even grilling at all!) got stuck in some people’s minds as the One Holy True Definition.
When you get into people using the One Holy True Definition you know they lost the argument.
Every state in the southern United States has the One True Method of barbecuing, and they’re all different. While some are clearly wrong (like Alabama’s use of mayonnaise-based sauce), there’s no consensus.
I thought they were nouns … “I cleaned the grill in the BBQ before I started cooking.” … the verb is “to cook” … but maybe that’s just me …
Interesting. I’ve never heard “grill” used for any cooking involving an oven.
I’m reasonably active in the barbeque hobby community and these definition debates come up all the time. Different words for a given meaning is common and no one is right or wrong… except the guy loudly protesting for ‘proper’ usage. He’s wrong.
I personally use ‘smoke’ for low & low cooking.
It’s a British vs American English thing.
Cecil is from Chicago. He has odd ideas about hot dog toppings, and things that Chicago style pizza is edible.
British grilling = American broiling. I.e. heat coming from above, such as the broiler grate in most ovens, or a separate compartment in some (“salamander”).
No putting sauce on something doesn’t make it BBQ. But my mind usually goes to the wet styles first, not dry rub.