Hi,
I heard about different terminologies such as: coating, insulation, cladding and lining. Following is my understanding for their definitions:
*Insulation is used to prevent the heat loss (in HE, for example) or to prevent galvanic corrosion.
*Coating is used to prevent external corrosion.
*Cladding uses a layer of expensive metal say CRA to protect the inexpensive metal that tends to corrode much easier. so, it reduces the overall cost.
*Lining uses non-metals, paint, spray, glass..
If you captured a major misunderstanding in the above concepts, I would appreciate your corrections.