aggression vs violence

aggression and violence both are nouns.

Word	Noun	Adjective	Verb	Adverb
aggression	Yes	No	No	No
violence	Yes	No	No	No

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

Other hyponyms of aggression include meat grinder, force, pillage, pillaging, plundering.

aggression (noun)	violence (noun)
violent action that is hostile and usually unprovoked	an act of aggression (as one against a person who resists)
deliberately unfriendly behavior	the property of being wild or turbulent
the act of initiating hostilities	a turbulent state resulting in injuries and destruction etc.
a disposition to behave aggressively
a feeling of hostility that arouses thoughts of attack