Hi John, just try out everything – don’t worry to ask. 
The “Auto mask”, the “Brush” (= manual mask) and the “Graduated Filter” (= gradient mask), these three are ‘normal’ masks and affect the masked area in relation to the mask’s strength, but otherwise without differentiating.
With “Control Points”, the radius determines the range of influence spreading like a circle gradient, but the selection is based on colour & lightness of the placed point.
have fun, Wolfgang
further information / different workflow
→ Expanding / Contracting tools with a Wacom Tablet and stylus - #4 by Wolfgang