Basically:

Utilitarianism - a 'good action' in ethics is whatever results in the most utility

Preference Utilitarianism - we should do whatever creates the most utility, and "utility" here refers to meeting the preferences of persons

contrast with

Hedonistic Utilitarianism - we should do whatever creates the most utility, where "utility" means a sliding scale of pleasure and pain. There are many variations on this.

Average Preference Utilitarianism - we should do whatever fulfils the greatest average (usually mean) of preferences across all persons

contrast with

Total Preference Utilitarianism - we should do whatever fulfils the most preferences across all persons

Negative Average Preference Utilitarianism - we should do whatever, on average, avoids preventing preferences across all persons

Which is why /u/Archibald-Wisconsin says it:

is exactly what it sounds like and focuses on the frustration of preferences

If you want to know about more conventional Utilitarianism, I would recommend Singer's The Most Good You Can Do, and then Parfit's On What Matters, Vol. 1 for an approach by a sympathetic non-Utilitarian.

It's an ethical theory with a lot of heft outside philosophy, so it's worth knowing something about! For example, many vegetarians, vegans, neo-Malthusians/anti-natalists and almost all effective altruists (like Bill & Melinda Gates!) depend on Utilitarian assumptions for their actions. So it has a huge impact on the world.

I agree with Archibald-Wisconsin that ultimately the wordiness of theories like Chao's suggests that hey, maybe it's time to possibly perhaps think about moving away from Utilitarianism for this guy.

I think it loses some of the persuasive or intuitive power and appeal of simpler Utilitarianisms, and ties itself up in knots seeking to avoid conclusions that the author finds unpalatable (where a more orthodox Utilitarian would tend to 'bite the bullet' and accept the results as ethical).