insult vs vitriol

insult and vitriol both are nouns.

Word	Noun	Adjective	Verb	Adverb
insult	Yes	No	Yes	No
vitriol	Yes	No	Yes	No

As nouns, vitriol is a hyponym of insult; that is, vitriol is a word with a more specific, narrower meaning than insult:

insult: a rude expression intended to offend or hurt
vitriol: abusive or venomous language used to express blame or censure or bitter deep-seated ill will

Other hyponyms of insult include low blow, billingsgate, scurrility, cut, stinger, invective, vituperation.

insult (noun)	vitriol (noun)
a deliberately offensive act or something producing the effect of deliberate disrespect	abusive or venomous language used to express blame or censure or bitter deep-seated ill will
a rude expression intended to offend or hurt	(H2SO4) a highly corrosive acid made from sulfur dioxide; widely used in the chemical industry

insult (verb)	vitriol (verb)
treat, mention, or speak to rudely	subject to bitter verbal abuse
	expose to the effects of vitriol or injure with vitriol