Undermount slides offer two benefits that side-mount slides do not: they are totally concealed beneath the drawer, and, since they don't require as much space on the sides for clearance, they offer slightly more storage area inside the drawer.

Are undermount drawer slides better?

Undermounts, however, are far less susceptible to this dust accumulation, resulting in more durable hardware and a more sanitary environment. Moreover, slides on the underside of drawers makes cleaning up spills much easier. Even with undermount drawer glides, spills will happen.

What is the difference between undermount and bottom-mount drawer slides?

Bottom mounts are attached to the bottom of the drawer and side of the cabinet. Meanwhile, undermounts are two slides attached to the underneath (invisible) of the drawer and side of the cabinet.