if you apply a force to a brittle materials this won't deform plastically. but will suddenly snap when the force gets to a certian size. brittle materials can be quite weak if the have crack in them.
the shape can be change of a ductile materials, that drawing them into wires or other shapes.
important there keep their strength when there deformed like this
malleable materials can changed fairly easily by the term of hammering or rolling. the differenct between malleable and ductile materials is that malleable materials won't neccessarily keep their strength.
dent or scratch a hard material you will probably have very little effect. the structure means hard materials are resistant to cutting indentation and abrasion
the chaging shape of stiff materials is really diffcult as they are resistant to both bending and strecthing.
stiffness is measured by Young Modules.
toughness is measured of the engry a materials can absorb before it breaks. really tough materials can abosred a lot of energy so are very difcult to break.