Can't answer about the driver but
Buck and boost are two types of DC/DC switching convers
- The Buck converter is for lowering the voltage, the usb adapter (5V) that you connect to a car battery (12V) is one example, sometimes used in flashlight driver for driving low Vf led with a Li-ion battery
- The Boost converter is when the voltage required for the load is higher than the source voltage like when you want to supply a 3V led from a 1.5V battery
- Buck/Boost converters exist too and can theoricaly combine the two functions, like driving a load that require 3.2V from a battery that can go from 4V to 2.5V