The model simulates buck converter using different approaches. Parameters can be change from the initializing callback function in the model properties. First circuit implements buck using a MOSFET and diode, second implements using two MOSFETs and third implements using the model equation. Power switches voltage drop is neglected in the third implementation, that's why output voltage is higher than the first two implementations.
The model can be simulated for different duty ratio to clear the concept of buck converters.