human ecology vs demography

human ecology and demography both are nouns.

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

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

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

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