defamer vs maligner

defamer and maligner both are nouns.

Word	Noun	Adjective	Verb	Adverb
defamer	Yes	No	No	No
maligner	Yes	No	No	No

As nouns, defamer and maligner are synonyms defined as:

defamer and maligner: one who attacks the reputation of another by slander or libel

Other synonyms of defamer include backbiter, libeler, slanderer, traducer, vilifier.

defamer (noun)	maligner (noun)
one who attacks the reputation of another by slander or libel	one who attacks the reputation of another by slander or libel