Maybe a difference in terminology.
In my mind both a pump and motor come from the mfgr with a baseplate and bolt holes, for leveling and attaching those items to anything, a skid, the floor, a support of some kind, or a foundation.
A skid, is for ease of transport, lifting, hauling, pulling in place, the motor, pump and gearbox as a single unit, or perhaps as individual units with independent skids, for setdown directly on a pad, floor, foundation or support of some kind. A skid is usually optional. Baseplates are attached to the skid. If no skid is provided, the units would be bolted directly, baseplate to floor, to foundation, or to some other type of support.
If a skid is provided, the units would be leveled, aligned and bolted (or welded) to the skid and the skid would be bolted to the floor, foundation, or simply set on a concrete pad, or, if small units, with skid set directly on soil.