assaulter vs aggressor

assaulter and aggressor both are nouns.

Word	Noun	Adjective	Verb	Adverb
assaulter	Yes	No	No	No
aggressor	Yes	No	No	No

As nouns, assaulter and aggressor are synonyms defined as:

Other synonyms of assaulter include assailant, attacker.

assaulter (noun)	aggressor (noun)
someone who attacks	someone who attacks
	a confident assertive person who acts as instigator