aggression vs ill will

aggression and ill will both are nouns.

Word	Noun	Adjective	Verb	Adverb
aggression	Yes	No	No	No
ill will	Yes	No	No	No

As nouns, ill will is a hypernym of aggression; that is, ill will is a word with a broader meaning than aggression:

Other hypernyms of aggression include enmity, hostility.

aggression (noun)	ill will (noun)
violent action that is hostile and usually unprovoked	a hostile (very unfriendly) disposition
deliberately unfriendly behavior	the feeling of a hostile person
the act of initiating hostilities
a disposition to behave aggressively
a feeling of hostility that arouses thoughts of attack