Buck converter can be synchronous or non-synchronous type. The former uses a MOSFET (or BJT, IGBT) in place of the buck diode. Basically, there are two switches in synchronous type. On the other hand, the latter uses a switch and a diode combination. This is simpler and cheaper than the former since there is only a single MOSFET to control.
READ![mosfet selection for buck converter](https://i0.wp.com/electronicsbeliever.com/wp-content/uploads/2023/09/fig-2-1.png?resize=650%2C279&ssl=1)