sociology vs demography

sociology and demography both are nouns.

Word	Noun	Adjective	Verb	Adverb
sociology	Yes	No	No	No
demography	Yes	No	No	No

As nouns, demography is a hyponym of sociology; that is, demography is a word with a more specific, narrower meaning than sociology:

sociology: the study and classification of human societies
demography: the branch of sociology that studies the characteristics of human populations

Other hyponyms of sociology include criminology, human ecology, psephology, sociometry, psychographics.

sociology (noun)	demography (noun)
the study and classification of human societies	the branch of sociology that studies the characteristics of human populations