Article :: Eight Aspiration vs Eight House

Eight Aspiration is based on the Bagua static layout of the Eight Trigram. This is thus a static model which does not personalise to a single person.
Eight House / Eight Trigram is the very basic concept which expands upon the Bagua, that tries to personalise a person into the calculation.
Given that there are Eight Directions and each direction is often related to a compass direction. It was thus derived to be called the Compass School.
This theory uses numerology to try to fit a person based on his Year of Birth which will thus arrange the Eight Trigram in such a way that you can see 4 good and 4 bad direction.
The Eight Trigam is a basic foundation for the Advanced Compass School called the Flying Star (Xuan Kong Feng Shui). As it further divides the each of the direction into 3 sub-sectors. Thus, the 8 directions later becomes 24 mountain directions.
It also provides the basic foundation of how the initial Flying Star formation is layout. And thus a way for the Flying Star to fly in a unique formation.
This Same Eight Trigam when arranged in different way produces different types of Bagua formation.
So fundamentally, it is a very simplified form of this very easy to apply Eight House Theory.
However, despite it's ease of use and very simplified model, it is still very useful in determining how suitable a direction is to a person. But it is less accurate then a later concept called the Ba Zi Feng Shui 24 directions.
Weakness of this Theory
This theory only bases on the Year of Birth so it's accurately is limited. But it is good enough to allow it to be used as a general 4 good and 4 bad directions. Thus, determining a portion of the suitability of the Earth Luck to a person.