iniquity vs transgression

iniquity and transgression both are nouns.

Word	Noun	Adjective	Verb	Adverb
iniquity	Yes	No	No	No
transgression	Yes	No	No	No

As nouns, transgression is a hypernym of iniquity; that is, transgression is a word with a broader meaning than iniquity:

iniquity: morally objectionable behavior
transgression: the act of transgressing; the violation of a law or a duty or moral principle

Other hypernyms of iniquity include evildoing.

iniquity (noun)	transgression (noun)
morally objectionable behavior	the act of transgressing; the violation of a law or a duty or moral principle
an unjust act	the action of going beyond or overstepping some boundary or limit
	the spreading of the sea over land as evidenced by the deposition of marine strata over terrestrial strata