“The difference between malleability and ductility is that malleability is the ability to deform easily upon the application of a compressive force, and ductility is doing the same with tensile force.

*Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically without fracture.

In material science, ductility specifically refers to a material’s ability to deform under tensile stress; this is often characterized by the material’s ability to be stretched into a wire.

Malleability, a similar concept, refers to a material’s ability to deform under compressive stress; this is often characterized by the material’s ability to form a thin sheet by hammering or rolling. Ductility and malleability do not always correlate with each other; for instance, gold is both ductile and malleable, but lead is only malleable. ”

Source: http://answers.yahoo.com/question/index?qid=20090303051823AAFRJmT