The difference between moisture content and rh is the moisture content measures the amount of water in the item tested, rh is the amount of water vapor in the air in a space. There is a way to convert moisture content to r/h but you have to know the volume of item tested, which is difficult with buds because of air spaces and irregular shapes. It’s easier to use r/h, and the meters are cheap and readily available. The best drying method is low (temp) and slow (rh). Drying at 60 degrees and 60% humidity are good numbers to shoot for.