Scroll down a bit in this article. There’s a list of what each of the available keys are required to provide. A “key” in this context is basically a notch in a certain location, which then defines the meaning of the various pins of the connector. Some devices have multiple keys, as some of the specifications have a common subset. Like key A+E is common, because E provides almost everything that A does, so a device that only requires the common interfaces can work in both. Cars that rely on one of the exclusive interfaces will have the specific key of course. This A+E communication is often used for WiFi cards.
Sockets always only have one key though, for obvious reasons.
Edit: correction/clarification
Flamethrowers typically set fire to a stream of flammable liquid, like gasoline (as a trivial example). Torches use gas, or gas mixtures.
The inherent range differences are a meter (maybe 2) for torches, and flamethrowers do 50-100 m (source: Wikipedia). Just in case that isn’t clear, those aren’t the same category of device.