Dry, desiccate, dehydrate, bake, parch are comparable when meaning to treat or to affect so as to deprive of moisture.
Dry is the comprehensive word and may be used whatever the process (as evaporation, absorption, or solidification) or method (as heating, draining, or aerating) by which the result is attained.
Desiccate is narrower in its range of reference and implies a complete deprivation of moisture, especially of vital juices, and often therefore, in its common extended use, a withering or shriveling. It is applicable to animal and vegetable products preserved by thorough drying or it may be applied to persons or to their attitudes, activities, or expression which have lost all their spiritual or emotional freshness or vitality.
Dehydrate implies extraction or elimination of water; it is often preferred to desiccate, of which it is a close synonym, when the reference is to foods.
It is the usual word when the removal of water (or hydrogen and oxygen in the proportion to form water) is by chemical rather than physical means and in extended use suggests a removal of what strengthens, inspires, or makes meaningful or pleasing.
Bake implies not only dehydrating by means of heat, but a hardening or caking of what is dried.
Parch stresses the damaging effect of drying by intense heat or drought; it is preferred to bake, therefore, when the restoration of the proper amount of water is necessary or highly desirable.