This advantage is mostly just a clarification of Brachiator, to reflect animals that climb rapidly by scampering up rough surfaces rather than swinging. You get +2 to climbing skill and can move at half your basic move when climbing anything but smooth, flat surfaces.
The main difference is that true brachiation involves movement among branches, vines, and so on by grabbing them in your fist or other manipulator. Scansorial movement is along surfaces your claws can hook onto or sink into.