Originally Posted by
Ascended
Well, it's all sort of a case-by-case basis but generally it's a question of what degree of challenge can they reasonably, consistently, overcome, right? I vaguely rank it along these lines. And of course, there's tons of exceptions to everything and not everyone fits these definitions. And this is all based on what the character can consistently, reliably accomplish. Everyone can put in that extra effort and punch up sometimes, but I'm talking strictly "in their weight class" here.
Low-tier power levels can be physically challenged by powerless, baseline human enemies. If a dude with a crowbar has a semi-reasonable chance to KO you, you're probably low-tier. Low-tier characters are, typically, going to be dealing with "real world" crime; drugs, human trafficking, smuggling, organized crime, etc. They may act locally, or globally, but will rarely find themselves in fantastical locales such as space or other dimensions. The scope of their actions rarely has direct implications for more than a city, or a very specific global network. A low-tier character can have powers, but rarely has more than one, or a very closely related set. Power limits are like "can reliably pick up a armored truck with some effort" and "reliably, consistently blow up a concrete wall" or "short out every circuit in this modestly sized building."
Mid-tier power levels are much more clearly beyond the scope of humanity or real world technology. A baseline human can still be a threat, but it will require the human have something extra in his advantage; numbers, high-tech gear, world class training, etc. A dude with a crowbar can still get a lucky hit in, but when a mid-tier character fights baseline humans, he's noticeably punching below his weight class. The scope of their actions can have direct implications on anything from a city to the globe, but will rarely extend beyond that. Threats will include "real world" problems but will also include fantastical threats like alien invasions or giant monsters, and common locations may include different planets, dimensions, timelines, etc. A mid-tier character either has powers or equipment that eclipses real world technology/knowledge. They can not only pick up the armored truck, but might throw it through a building a block away. They won't just knock down a wall, they'll knock down the whole building. They won't just short out every circuit in the building, but the entire city.
High-tier characters aren't challenged by baseline humans, excepting plot-induced reasoning. A baseline human with the best technology/knowledge on earth is damn unlikely to hurt the high-tier character. The scope of the high-tier character starts at a global level and often has direct implications for the solar system, if not the galaxy, universe, or more. If they deal with "real world" problems it carries global implications, and they operate in fantastical locales as often or more often than they do a standard, grounded setting. They can throw that armored truck into the sun or into the future, destroy a continent, and short out every circuit on the planet.