What types of mechanical ventilation are there?

There are two types of controlled mechanical ventilation with heat recovery:
Ventilation with decentralized heat recovery: It consists of placing a single-insulated system on each exterior wall that takes fresh air from the outside and extracts stale air from the inside, causing a heat exchange between both airflows.
Ventilation with centralized heat recovery: It consists in centralizing the ventilation at a point where the air arrives and leaves to the different rooms of the house through an invisible network of ducts housed in the false ceiling or wall.