Form School describes the flow of chi in relation to structures and forms in a landscape or a building. It also talks about the quality of the chi and how to collect much of the beneficial energy throughout a house.
Compass School is based on energetic observations on flat land without much topography. People focused on seasonal influences, repeating cycles, star constellations using the various compass directions in conjunction with aspects of time. Flying Stars, Ming Gua and Eight Mansions are all specific systems to calculate the most beneficial influences of space and time.
Compass school techniques are taught by a few masters in the west. Because of the complex calculations it takes a lot of practice and they are considered "higher" forms of Feng Shui. There are different ancient books and formulas which give advice how to analyze a situation or to increase prosperity and determine good timing for important events.