How do high island differ from low island?

High Islands are large mountains and are formed from volcano. They have fertile soil and can grow crops. 
Low Islands are the opposite, they have poor soil and cannot produce crops. 

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.