scantiness vs inadequacy

scantiness and inadequacy both are nouns.

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

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

Other hypernyms of scantiness include deficiency, insufficiency.

scantiness (noun)	inadequacy (noun)
the quality of being meager	unsatisfactoriness by virtue of being inadequate
Of a garment, the property of being very small, light, or revealing.	lack of an adequate quantity or number
	a lack of competence