demographist vs demographer

demographist and demographer both are nouns.

Word	Noun	Adjective	Verb	Adverb
demographist	Yes	No	No	No
demographer	Yes	No	No	No

As nouns, demographist and demographer are synonyms defined as:

demographist and demographer: a scientist who studies the growth and density of populations and their vital statistics

Other synonyms of demographist include population scientist.

demographist (noun)	demographer (noun)
a scientist who studies the growth and density of populations and their vital statistics	a scientist who studies the growth and density of populations and their vital statistics