shortfall vs inadequacy

shortfall and inadequacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
shortfall	Yes	No	No	No
inadequacy	Yes	No	No	No

As nouns, inadequacy is a hypernym of shortfall; that is, inadequacy is a word with a broader meaning than shortfall:

shortfall: the property of being an amount by which something is less than expected or required
inadequacy: lack of an adequate quantity or number

Other hypernyms of shortfall include deficiency, insufficiency.

shortfall (noun)	inadequacy (noun)
the property of being an amount by which something is less than expected or required	unsatisfactoriness by virtue of being inadequate
	lack of an adequate quantity or number
	a lack of competence