I usually call this device a pallet, but I have heard it referred to as a skid:
Is there a difference between the two words (such as one is the name of the actual wooden device, the other is the combined name for the wooden "slab" and the contents stacked on top), or are they entirely synonymous?
From my experience in the American metal fabricating industry, I would say that the two terms are often used interchangeably, but not always.
A wooden platform for stacking and moving product with a forklift or pallet jack could be called a pallet or a skid. They are equivalent when speaking generally without reference to a specific sub-type: "How many pallets/skids will fit on that truck?"
A steel item of similar shape and purpose is almost always a skid or a metal skid. Those would typically be for in-plant use because of their expense and great durability.
A plastic item of this class would usually be called a pallet or recyclable pallet. Recyclable pallet can actually mean two different things: a plastic or wood platform that is supposed to be returned to a supplier to be used again, or a wooden pallet that was salvaged, repaired, and resold at a discounted rate.
The tool pallet jack is common, but skid jack is almost unheard of.
Pallet can be be made into a verb as palletize, but skid rarely becomes skidded.
When referring to wooden transport platforms, the pallet has runners, top, and bottom slats.
The top slats are the foundation for the object being transported. The runners are 2x4’s or 4x4’s that attach to the underside of the top slats. They are usually supporting slats that are attached to the bottom side of the pallets runners for added strength. Four way pallets can accept a forklift tongue from either of all 4 sides, and the 2 way pallet, two sides.
When the pallet lacks the bottom attaching slats and just rests on runners, it’s called a skid. Voila!
From etymonline.com
(http://www.etymonline.com/index.php?term=skid&allowed_in_frame=0)
skid (n.) c.1600, "beam or plank on which something rests," especially on which something heavy can be rolled from place to place (1782), of uncertain origin, probably from a Scandinavian source akin to Old Norse skið "stick of wood" (see ski (n.)). As "a sliding along" from 1890; specifically of motor vehicles from 1903. Skid-mark is from 1914.
(http://www.etymonline.com/index.php?allowed_in_frame=0&search=pallet&searchmode=none)
pallet (n.2) "flat wooden blade" used as a tool by potters, etc., early 15c., from Middle French palette, diminutive of pale "spade, shovel" (see palette). Meaning "large portable tray" used with a forklift for moving loads is from 1921.
I'm putting in the other use of pallet because I think it might be related.
pallet (n.1) "mattress," late 14c., from Anglo-French paillete "straw, bundle of straw," Old French paillet "chaff, bundle of straw," from paille "straw" (12c.), from Latin palea "chaff," perhaps cognate with Sanskrit palavah, Old Church Slavonic pleva, Russian peleva, Lithuanian pelus.
The use of pallet as a "'large portable tray' used with a forklift for moving loads," seems to stem from the word's use as a mattress.
The website @Barmar posted has a good history.
Pallet refers to the constructed device to put goods on for transport. A skid pallet is a particular dimension of pallet.
Here in Australia a conventional pallet is 1200mm X 1200mm
A "Skid Pallet" is 600mm X 1200 (so half)
