“Shop” typically are hardwood sheets that can have imperfections from the manufacturer
MDF is medium density fiberboard. VC is veneer core or plywood. C/C is chip core.
COMBO CORE is a combination plywood core and thin MDF sheet layer directly below the veneer.
UV is a finish that is applied to the plywood that can be clear coat or have a stain.
MILL stands for Mill option back. This is a veneer that is used to balance the board which is chosen for utility not looks.