injustice vs wrongdoing

injustice and wrongdoing both are nouns.

Word	Noun	Adjective	Verb	Adverb
injustice	Yes	No	No	No
wrongdoing	Yes	No	No	No

As nouns, wrongdoing is a hypernym of injustice; that is, wrongdoing is a word with a broader meaning than injustice:

Other hypernyms of injustice include actus reus, misconduct, wrongful conduct.

injustice (noun)	wrongdoing (noun)
an unjust act	activity that transgresses moral or civil law
the practice of being unjust or unfair	departure from what is ethically acceptable