absence vs nonattendance

absence and nonattendance both are nouns.

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

As nouns, nonattendance is a hypernym of absence; that is, nonattendance is a word with a broader meaning than absence:

absence (noun)	nonattendance (noun)
failure to be present	the failure to attend
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