demographer vs sociologist

demographer and sociologist both are nouns.

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

As nouns, sociologist is a hypernym of demographer; that is, sociologist is a word with a broader meaning than demographer:

demographer: a scientist who studies the growth and density of populations and their vital statistics
sociologist: a social scientist who studies the institutions and development of human society

demographer (noun)	sociologist (noun)
a scientist who studies the growth and density of populations and their vital statistics	a social scientist who studies the institutions and development of human society