Allotropy and polymorphism
In my own work, I've never used the term polymorph for anything but molecular crystals in a highly but differently ordered solid state.


  In the case of crystal solids, it seems clear that allotropy is a particular case of polymorphism.


Yes, allotropy is the polymorphism of elements in the same state. This does not mean that each solid allotrope has to be highly ordered: amorphous forms of carbon, phosphorus or selenium are considered as allotropes too.

The definition of allotropy isn't confined to the solid state: ozone is an allotrope of dioxygen.