victimisation vs mistreatment

victimisation and mistreatment both are nouns.

Word	Noun	Adjective	Verb	Adverb
victimisation	Yes	No	No	No
mistreatment	Yes	No	No	No

As nouns, mistreatment is a hypernym of victimisation; that is, mistreatment is a word with a broader meaning than victimisation:

victimisation: an act that exploits or victimizes someone (treats them unfairly)
mistreatment: the practice of treating (someone or something) badly

victimisation (noun)	mistreatment (noun)
an act that exploits or victimizes someone (treats them unfairly)	the practice of treating (someone or something) badly