Each brand is trying to find a way to get a leg up on the competition in a tight market space. The above picture is what I found on my last grocery run. What caught my eye was the asterisk next to the non-GMO popcorn claim. My guess was the ingredients list would include soybean, canola, or corn oil.
The temperature for broiling in an oven is 260 degrees Celsius or  500 degrees Fahrenheit. Medium heat is about 177 degrees Celsius or  350 degrees Fahrenheit.
Controlling the Temperature. The biggest difference between a grill and an oven broiler is that your oven has a thermostat to control temperature. While this might seem like it would simplify the process the problem is that your oven can turn off when it gets to a certain temperature -- about 500 to 550 degrees F (260 to 288 degrees C). This will leave foods to cook in their own steam. You want that constant direct heat.