atavist vs throwback

atavist and throwback both are nouns.

Word	Noun	Adjective	Verb	Adverb
atavist	Yes	No	No	No
throwback	Yes	Yes	No	No

As nouns, atavist and throwback are synonyms defined as:

atavist and throwback: an organism that has the characteristics of a more primitive type of that organism

atavist (noun)	throwback (noun)
an organism that has the characteristics of a more primitive type of that organism	a reappearance of an earlier characteristic
	an organism that has the characteristics of a more primitive type of that organism

atavist (adjective)	throwback (adjective)
	characteristic of an atavist