There are three main types of Awase(cladding) used in Japanese(and western) knifemaking:
Ni-Mai - Awase type forging for the single bevel(Kata Ha) knife. Cladding is applied only on the cutting edge side of the blade, Ura(back side) is hagane, or hard steel.
San-mai - Technique of welded steel that laminates the hard core of the blade with softer outer layers. Basically, this is Awase on
both sides of the Hagane, but not over the spine.
Warikomi - Type of cladding, Jigane applied on the sides and the spine of the
Hagane.
Occasionally Warikomi is used interchangeably with San-Mai, but it is a different type of awase(cladding) as you can see from the diagram.
