In QM, the hands or forearms interact with the surface of contact through simple pressing, possibly with a light clawing to improve traction. When the hands start grabbing the surface they're on, the movement becomes a form of climbing. In a sense, climbing is just a specialized form of QM! In both, the arms are used as much if nt more than the legs, however in climbing the arms are pulling and pushing, while QM only involves pushing movements. Note that the pushing of the arms, using triceps and back shoulder muscles, is generally easier than the pulling, with biceps and deltoid.
When progressing on a slope, QM and climbing can sometimes merge. QM movements on a slope upward are made easier as the hips are lower, decreasing the effort of the arms. The body can be spread further. On downward slopes it is the opposite: one must shorten the distance between the limbs in order to maintain a vertical alignment of the joints and contact points. On steep slopes, it is much advantageous to turn around and progress backward, feet first. In general it is best to keep the head toward the upper part of the slope and the front of the body facing it. To avoid or slow down a fall, the quadrupedist can always drop to the ground and move by crawling, thus increasing the area of contact with the slope. Going sideways can be good to progress up and down a slope, either as a crab or using a sideways posture halfway between crawling and regular QM.