demography vs human ecology

demography and human ecology both are nouns.

Word	Noun	Adjective	Verb	Adverb
demography	Yes	No	No	No
human ecology	Yes	No	No	No

As nouns, demography and human ecology are synonyms defined as:

demography and human ecology: the branch of sociology that studies the characteristics of human populations

demography (noun)	human ecology (noun)
the branch of sociology that studies the characteristics of human populations	the branch of sociology that studies the characteristics of human populations