deficiency vs shortfall

deficiency and shortfall both are nouns.

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

As nouns, shortfall is a hyponym of deficiency; that is, shortfall is a word with a more specific, narrower meaning than deficiency:

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

deficiency (noun)	shortfall (noun)
lack of an adequate quantity or number	the property of being an amount by which something is less than expected or required
the state of needing something that is absent or unavailable