allegation vs accusation

allegation and accusation both are nouns.

Word	Noun	Adjective	Verb	Adverb
allegation	Yes	No	No	No
accusation	Yes	No	No	No

As nouns, accusation is a hypernym of allegation; that is, accusation is a word with a broader meaning than allegation:

allegation: (law) a formal accusation against somebody (often in a court of law)
accusation: a formal charge of wrongdoing brought against a person; the act of imputing blame or guilt

Other hypernyms of allegation include accusal.

allegation (noun)	accusation (noun)
(law) a formal accusation against somebody (often in a court of law)	a formal charge of wrongdoing brought against a person; the act of imputing blame or guilt
statements affirming or denying certain matters of fact that you are prepared to prove	an assertion that someone is guilty of a fault or offence