Active
The Active Layer button causes information (such as orientation, depth, color and material) to be picked only from the active layer, and all other layers are ignored.
Other
The Other Layer/s button causes information (such as orientation, depth, color and material) to be picked only from the other layers, and the current layer is ignored.
All
The All Layer/s button causes information (such as orientation, depth, color and material) to be picked from all layers.
Dynamic
When applying brushstrokes, information is constantly picked from the canvas and used to update the stroke. If Dynamic drawing is turned off, the current brush stroke is ignored while picking the information, until the mouse/pen button is released. If it’s turned on, the information is picked both from the canvas and from changes made by the current brush stroke.
Reference Guide > Picker> Source