deficiency vs absence

deficiency and absence both are nouns.

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

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

Other hyponyms of deficiency include dearth, famine, shortage, deficit, mineral deficiency, shortness, stringency, tightness.

deficiency (noun)	absence (noun)
lack of an adequate quantity or number	failure to be present
the state of needing something that is absent or unavailable	the state of being absent
	the occurrence of an abrupt, transient loss or impairment of consciousness (which is not subsequently remembered), sometimes with light twitching, fluttering eyelids, etc.; common in petit mal epilepsy
	the time interval during which something or somebody is away