تفاوت بین الاستیسیته و انعطاف پذیری

Flexibility and elasticity are two different things. For example, rubber is mainly elastic and flexible (ductile) material, whereas glass (at room temperature) is also elastic but rigid (brittle). Flexibility of a material is a character related to the toughness property of the material, not to its elasticity; it is resistance against impact loading. So, an elastic material can be highly tough (ductile) or can be brittle. We can say that, elasticity is resistance of material against deformation, while ductility is related to the amount of energy that materiel can absorb during deformation. Glass is much stiffer and more elastic than rubber, but it breaks easier with much less energy. Rubber is tougher than glass but less stiff.

For the materials A and B in the question: Material A with high elastic modulus deforms much less than material B with smaller modulus. Because B deforms with much less force (stress), we can say that it is more flexible than A.