usurper vs supplanter

usurper and supplanter both are nouns.

Word	Noun	Adjective	Verb	Adverb
usurper	Yes	No	No	No
supplanter	Yes	No	No	No

As nouns, usurper and supplanter are synonyms defined as:

usurper and supplanter: one who wrongfully or illegally seizes and holds the place of another

usurper (noun)	supplanter (noun)
one who wrongfully or illegally seizes and holds the place of another	one who wrongfully or illegally seizes and holds the place of another