Never mind what the description said about "in the game" for now, and just read it as "in your area". That global limit says how many of that kind of mob you generally want to have in your area before the hunters arrive. That's TOTAL. If they walk around, they may be spread out. But the total maximum will be maintained, if your local maxima allow it.
The local maximum applies to the particular mob and the particular room you coded. It's a kind of population explosion limiter for that room. If your mobs can wander, your number of mobs in that room may never hit the limit you set, but mobs being loaded into that room and wandering around your area will contribute to the global maximum. Once the global maximum is reached, no more mobs will be loaded in any of your rooms! Not until someone kills a few off, anyway.
If your local maxima are too high, mobs will be loaded in the first few of your rooms (maybe only one) until the global maximum is reached, and never again will any mobs load in the other rooms because the global population puts a lid on things as soon as mobs are replaced in the first room or two. Putting your local maxima up close to your global max or even higher results in one or two crowded rooms which will always be bursting with mobs, and rooms further down the line perpetually empty. Worse, if those mobs happen to be of the assisting kind, that first room will be practically unplayable because it will always have too many of that kind of mob in it; while the other rooms will be unplayable for lack of prey.
A sensible example: Set a global maximum of 10 mobs for a particular type. Let those mobs reset in 5 different rooms, with a local maximum of 2 in each. That should make for a happy, balanced population. You will probably be working with smaller numbers yet unless you're populating a city the size of Midgaard.
The truth is, each of these reset lines runs sort of independently and will act in accordance with whatever limits you tell it. Each of these reset lines believes the global limit you code in it to be the true and only global limit. If you code different global limits into different lines, the ones with the low limits will stop 'producing' earlier and the other ones will keep working up to the higher limit they were told about. In general, this doesn't result in a healthy balance and 'production' of mobs (or objects), so you are better advised to code the same "global limit" value into all mobs (or objects) of the same vnum. It saves confusion for everyone concerned.