There’s a few different things here that make clarity difficult. One is the precise definition of various techniques, for example:poaching water is not bubbling, simmering water is gentle bubbles, boiling water is bubbling heavily(some say “full rolling boil”, which is what boiling always is. Second is simply the name of the cooking vessel/equipment, griddle vs grill vs broiler, which is sometimes the same term used to describe the technique applied. You can grill a steak, but you wouldn’t say you ovened a roast. Last is that many terms are misused so much that it’s just become common parlance. Technically a grill is a device with grates and a radiant device that cooks food through a combination of conduction and radiation, usually powered by propane or natural gas. A BBQ is a similar object powered by wood, but it’s common for an outdoor grill to be referred to as a BBQ, though when used with the lid down is a little different than an open restaurant style grill since it acts a bit like an oven too.
I’ve had a few different First Aid courses and the instructors all have slightly different reasoning. One argument for compression only is potential for passing disease mouth to mouth, the newer courses tend to teach this because sometimes people that don’t feel comfortable doing rescue breaths will fail to do CPR at all. Another is that in cases where you’ve witnessed the event, the blood is already fairly well oxygenated and if medical help has a good response time the benefits of breaths are minimal. The first is more about compression only CPR being better than nothing, breaths are still advised where the rescuer feels comfortable doing so. The second is pretty situational.