To dismantle a common misconception:  There is no such thing as espresso beans.  Rather, coffee roasted for preparing espresso is a blend of selected regional beans combined in varying degrees of roast levels.  Espresso itself is brewed coffee, not a type of bean.  Today there are industry standards but each specialty coffee roaster takes liberties in flexing boundaries and creating an individual profile for their espresso blend.
  Blending     Espresso     History     Roasting