Flamethrowers launch a flammable liquid and can light that liquid. They have a longer range and the fuel they project generally sticks and continues burning after hitting a target. Propane torches just burn propane at their nozzle their range is much shorter and don't really pose a danger outside of a few feet. This [0] is a flamethrower and this is a propane torch [1].

The Tesla Flamethrower is literally just a roofing torch like in [1] with a plastic gun around it and the valve turned all the way open. [2]

[0] https://upload.wikimedia.org/wikipedia/commons/transcoded/3/...

[1] https://www.youtube.com/watch?v=UprliuSNvX0

[2] https://qz.com/1191685/elon-musks-boring-company-flamethrowe...